Canada, keen to diversify its exports away from the United States, says a deal with the European Union would increase two-way trade by 20 percent. The talks started in 2009.

Officials and industry sources say several sensitive matters remain to be settled, including access for agricultural goods, opening up procurement markets and the extension of pharmaceutical patents.

"I have not committed to a firm time line. We're not going to be rushed into a deal that doesn't serve Canadians," Fast said during a visit to Nigeria, where he was building bilateral trade ties with Africa's biggest oil producer.

"We continue to make significant progress in addressing the handful of remaining issues, which are the most serious and difficult ones to overcome," he said.

Fast said he would at some point meet with EU Trade Commissioner Karel De Gucht, likely in Ottawa, but no date had been set for that meeting. European officials say such a meeting is likely to take place on February 6-7.

Negotiators have struggled over investment protection, agriculture, public procurement and intellectual property, particularly regarding pharmaceuticals, trade experts say.

De Gucht told Reuters last week that the EU was ready to start talking about a free trade deal with the United States. European diplomats say this could give Canada further impetus to wrap up its own deal with the EU quickly before the bloc turns its attention to what would be a much richer agreement.

A free trade agreement with Canada, the EU's 12th-largest trading partner, would be the bloc's first with a country from the G7 group of major developed economies.

For Canada, it would be the most significant since the North American Free Trade Agreement with the United States and Mexico in 1994 and an opportunity to diversify exports away from the United States. The EU is its second-largest trading partner.

(Reporting by Joe Brock; editing by Ron Askew)

Just over a month after the shooting rampage in Newtown, Connecticut, experts told a Senate hearing that three-quarters of mental illnesses emerge by age 24, but fewer than one in five youths with diagnosable problems receive treatment that could avoid later problems including violence and suicide.

Overall, experts said as many of 45 million Americans experience mental illnesses such as depression, eating disorders, post-traumatic stress disorder and drug abuse each year. But only 38 percent get treatment.

"These are the chronic disorders of young people," said Dr. Thomas Insel, director of the National Institute of Mental Health.

The hearing, before the Senate Health, Education, Labor and Pensions Committee, was held in response to the shootings at Newtown's Sandy Hook Elementary School, where a young 20-year-old man described as having mental issues gunned down 26 people including 20 young children with assault rifle on December 14. It was the first time the committee has addressed the issue of mental health since 2007.

The Newtown tragedy and other mass shootings in recent years have ignited a debate about gun control and mental health, including a push by President Barack Obama for stronger gun controls and better mental health training for schools and communities.

But the committee's Democratic chairman, Tom Harkin, warned against drawing a bold parallel between mental illness and violence against others.

"One of the most insidious stereotypes about people with mental illness is that they are inherently violent," said the Iowa senator. "People with mental illness are much more likely to be the victims of violent crimes than they are to be perpetrators of acts of violence."

Insel said a relatively small number of mentally ill people, who suffer from symptoms such as paranoia and hallucinations, are violent. "Far more common than homicide is violence against the self," he said, pointing out that 90 percent of the 38,000 suicides each year involved mentally ill people.

RULES AND DEFICIT CUTS

All told, he said, the risk of violence, including suicide, among people who develop mental illness is 15 times greater without treatment.

Experts cautioned that treatment should avoid powerful drugs for children who are often vulnerable to side-effects and recommended extra care to ensure that the normal behavioral problems of childhood and adolescence not be mislabeled as mental illness.

In response to the Newtown tragedy, Obama has announced a series of initiatives intended to help teachers and other adults identify children, adolescents and young adults with mental illness and ensure they receive treatment.

Experts said Obama's healthcare reform law is expected to lead to the biggest increase in mental health access in a generation. After January 1, 2014, it is scheduled to extend health coverage to millions of Americans currently locked out of the $2.8 trillion U.S. healthcare system because of a lack of insurance.

Pamela Hyde, administrator of the U.S. Substance Abuse and Mental Health Services Administration, said that as many of 10 million people with mental illnesses could gain access to care as a result of the Patient Protection and Affordable Care Act. "Prevention works. Treatment is effective. And people recover," she said.

But Senator Patty Murray, a Democrat from Washington state, expressed concern that the Obama administration is not moving fast enough to produce detailed rules on how mental health access should be made available through new state-based online health insurance marketplaces being set up under the law.

"It's really essential that we see a final rule before April," Murray told Hyde. "Our states are working on the exchanges and they need that clarity. I can't urge you strongly enough."

Hyde said a final rule on essential benefits is due next month. But she could not say whether a separate rule on mental health parity would meet Murray's deadline.

(Reporting by David Morgan; Editing by Jilian Mincer and Tim Dobbyn)

FIFA said it maintained confidence in Brazilian authorities' security plans for the World Cup, but the event scheduled for Monday in the capital of Brasilia was called off in respect to the victims of the fire in the southern city of Santa Maria.

Organizers said they felt "extremely sad for what happened" and expressed "their sympathy to the families of the victims."

The unveiling of the official World Cup poster was scheduled for Monday but also was postponed. The poster will be unveiled Wednesday after a meeting of the local organizing committee in Rio de Janeiro.

FIFA Secretary General Jerome Valcke, who began a four-day visit to Brazil on Sunday, posted a message on his Twitter account expressing sympathies.

"Very sad to hear of the tragedy in southern Brazil. My condolences to the families of victims," wrote Valcke, who is scheduled to visit Fortaleza, Brasilia, Salvador and Rio de Janeiro in the center and north of the country.

Santa Maria is about 155 miles from Porto Alegre, among 12 World Cup host cities, in the same state of Rio Grande do Sul. The nightclub fire, which appeared to be the world's deadliest in more than a decade, is likely to again increase scrutiny of safety efforts ahead of the World Cup and the 2016 Rio de Janeiro Olympics. FIFA reiterated its belief that the local organizing committees and Brazilian city, state and federal agencies are up to the task.

"FIFA has full confidence in the security plans of the LOC and the local authorities," soccer's governing body said in a statement.

The 2016 Rio organizing committee expressed "solidarity with the families and friends of the victims of this tragedy," adding "it wishes a quick recovery to those affected."

The International Olympic Committee said that "we simply send our sympathies to friends and families."

Hosting the World Cup and Olympics two years apart has heightened attention on security and crime issues in Brazil, although the discussion has focused possible violence. South Africa's relatively high rates of violent crime were similarly scrutinized before the 2010 World Cup, but that tournament was held without major incident.

Because of the tragedy, the Rio Grande do Sul state soccer federation canceled Sunday matches in its first-division regional championship. There was a minute of silence honoring the victims before matches across the country.

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AP Sports Writers Graham Dunbar in Geneva and Tales Azzoni in Rustenburg, South Africa, contributed to this report.

From Syria to Mali, from Iran to the South China Sea, the United States' reluctance to be drawn into conflicts far from its shores was a leitmotiv of geopolitical debate at this year's World Economic Forum in Davos.

The absence of top Obama administration officials from the annual brainstorming and networking event in the Swiss mountains symbolized to some a perceived pullback from global leadership, even though it was Inauguration Week in Washington.

Leaders of Russia, Germany, Britain, Italy, South Africa, Jordan and many other nations made the journey.

U.S. bankers, business leaders and academics were out in force, but the most senior U.S. government officials were a Treasury undersecretary, an assistant secretary of state and the outgoing U.S. Trade Representative.

Delegates debated whether and when China would overtake America as the number one economy and global power -- estimates ranging from the early 2020s to never -- and what troubles were brewing while Washington remains in hands-off mode.

The ground rules of many Davos panels preclude identifying the speakers. One minister, shielded by that anonymity, lamented the dangers of "a world without American leadership".

Without U.S. involvement, one session was told, Syria would become a "Somalia on the Mediterranean", with Middle East states waging a proxy war via sectarian factions, some of which would export militant violence to the neighbors and to Europe.

Iran may accelerate its nuclear program to try to break out of isolation, Vali Nasr of Johns Hopkins University said, because Washington is squeezing it with economic sanctions but shunning either direct diplomatic engagement or military action.

"NEW TALIBAN IN SYRIA"

In a public address, King Abdullah of Jordan said his country, which had sent troops to fight Islamist militants in Afghanistan, now faces a "new Taliban in Syria", where an al-Qaeda affiliate has gained ground among forces fighting to oust President Bashar al-Assad. It could take years after the fall of Assad to "clean them out", the king said.

His fragile desert kingdom has taken in some 300,000 Syrian refugees, straining its thin resources and political stability. Some Syrian exiles present in Davos complained that Jordan has closed its border to Syrian opposition fighters.

Turkish Foreign Minister Ahmet Davutoglu, whose country has absorbed some 150,000 refugees and serves as a rear base for rebel fighters, said the international community would one day have to apologize to the Syrian people, as it had done in Rwanda, for failing to intervene to prevent massacres.

At least 60,000 people have been killed in two years of civil war in Syria, according to the United Nations.

Saudi Arabia's Prince Turki al-Faisal, a senior member of the royal family, former head of intelligence and ambassador to London and Washington, said the rebels were not receiving game-changing anti-aircraft and anti-tank weapons because of U.S. and manufacturers' restrictions on transfers to third parties.

U.S. strategic experts explained that Washington's sole interest in Syria was to prevent any threat to Israel and ensure chemical weapons did not fall into "terrorist" hands.

The same reluctance to be sucked into conflict meant Washington would provide little more than verbal and intelligence support for France as it battles in Mali against al-Qaeda-linked militants who have taken root in the vast ungoverned spaces of the Sahara and Sahel.

Few if any expect Obama, who burned his fingers in an early attempt to revive Israeli-Palestinian negotiations when Israeli Prime Minister Benjamin Netanyahu refused to stop Jewish settlement building, to launch a fresh peace initiative now.

Any risk of the United States being drawn into military intervention in the Islamic world after extricating itself from Iraq and winding down its presence in Afghanistan is anathema to the Obama administration, said Gideon Rose, editor of the policy journal Foreign Affairs.

ASIA PIVOT

Some delegates cited Obama's strategic "pivot" towards Asia, shifting Washington's focus towards the fast-growing economies of the Asia-Pacific region, as one reason why tensions were on the rise in the Middle East and North Africa.

The president's first foreign trip after his re-election in November to southeast Asia was overshadowed by a flare-up between Israel and the Palestinians in Gaza, a reminder of an issue on the back-burner that can explode at any time.

It came during a potentially dangerous phase in relations around east Asia between China and Japan, North Korea and its neighbors, and above all China and the United States.

Former Australian Prime Minister Kevin Rudd, a China expert, urged Obama to use his second term to take a major initiative to build a cooperative security relationship with China, partly to avert conflicts in the South China Sea. Rose doubted that the Obama administration would undertake anything so ambitious.

Wu Xinbo, dean of the School of International Studies at Fudan University in China, said Washington should start by ending aggressive air and sea patrolling off China's shores, which he said smacked of the "containment" of the former Soviet Union.

He voiced concern that Japan, driven by a more nationalist new government and public opinion, could pursue an "offensive" approach to a dispute over a group of small islands in the South China Sea known as Senkaku in Japan and Diaoyu in China.

Joseph Nye, a former U.S. official and Harvard academic who visited Japan and China recently as part of a semi-official U.S. delegation, said both countries were worried by the perceived growth of nationalism and militarism in the other although "this is not 1930s nationalism".

But Nye said both countries' new leaderships would give top priority to economic development and provided the United States sent careful messages to both, there was the prospect of a strong triangular relationship.

(Editing by Philippa Fletcher)

The drug, called solanezumab (sol-ah-NAYZ-uh-mab), is designed to bind to and help clear the sticky deposits that clog patients' brains.

Earlier studies found it did not help people with moderate to severe Alzheimer's but it showed some promise against milder disease. Researchers think it might work better if given before symptoms start.

"The hope is we can catch people before they decline," which can come 10 years or more after plaques first show up in the brain, said Dr. Reisa Sperling, director of the Alzheimer's center at Brigham and Women's Hospital in Boston.

She will help lead the new study, which will involve 1,000 people ages 70 to 85 whose brain scans show plaque buildup but who do not yet have any symptoms of dementia. They will get monthly infusions of solanezumab or a dummy drug for three years. The main goal will be slowing the rate of cognitive decline. The study will be done at 50 sites in the U.S. and possibly more in Canada, Australia and Europe, Sperling said.

In October, researchers said combined results from two studies of solanezumab suggested it might modestly slow mental decline, especially in patients with mild disease. Taken separately, the studies missed their main goals of significantly slowing the mind-robbing disease or improving activities of daily living.

Those results were not considered good enough to win the drug approval. So in December, Lilly said it would start another large study of it this year to try to confirm the hopeful results seen patients with mild disease. That is separate from the federal study Sperling will head.

About 35 million people worldwide have dementia, and Alzheimer's is the most common type. In the U.S., about 5 million have Alzheimer's. Current medicines such as Aricept and Namenda just temporarily ease symptoms. There is no known cure.

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Online:

Alzheimer's info: http://www.alzheimers.gov

Alzheimer's Association: http://www.alz.org

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Follow Marilynn Marchione's coverage at http://twitter.com/MMarchioneAP

Defense attorney Don Chairez said his client, Mazen Alotaibi, "probably" could post what Chairezcalled the "extraordinarily high" bail, surrender his diplomatic passport and be freed pending an evidentiary hearing Jan. 31.

But Chairez said he'd recommend to Saudi authorities the 23-year-old aircraft mechanic remain in jail until a Jan. 31 evidentiary hearing. The money would be better spent investigating the charges and preparing Alotaibi's defense, Chairez said.

He alleged outside court that his client was treated unfairly by police because he was too drunk on cognac Dec. 31 to surrender his right to have a lawyer present during questioning.

"Somebody who's under the influence cannot give up his right to an attorney," Chairez contended.

Alotaibi stood in court with an Arabic language interpreter and said nothing while Las Vegas Justice of the Peace Bill Kephart called the allegations against him "appalling." The judge noted that if Alotaibi fled the country, the U.S. and Saudi Arabia do not have an extradition treaty to bring him back.

"I don't know the truth of either side here," said Kephart, who will make the decision whether to move the case to state court if there is enough evidence for trial. The judge noted that Alotaibi faces "substantial consequences" if convicted.

Alotaibi is accused of forcing the boy into a Circus Circus hotel room where as many as four other Saudi officers smoked cigarettes or marijuana the morning before a New Year's Eve fireworks celebration on the Las Vegas Strip.

Prosecutor Mary Kay Holthus said Alotaibi acknowledged during police questioning that he had sex with the boy, who Holthus said was accosted by Alotaibi while headed to meet a friend and go to a doughnut shop at 7:30 a.m.

The prosecutor said that even if the boy sought sex, Nevada state law says a child under age 16 cannot give consent.

"I don't see that this is just, 'No big deal. Get drunk and have fun,'" Holthus said. "The likelihood of conviction is tremendous."

Chairez told the judge the boy wanted marijuana and refused repeated attempts by the Saudi men to get him to leave their hotel room.

"I do not believe there was any force here," Chairez said. "This is not a forcible rape. At most, if there was any sexual contact, it was consensual."

Saudi Arabian information official Nail Al-Jubeir in Washington referred questions about Alotaibi's case to Chairez.

Police reported collecting DNA evidence, a used condom and soiled towel from the bathroom where the boy said the attack took place. The boy lives out of state and had been staying at the hotel with his family, police said.

Chairez has said Alotaibi will plead not guilty to all charges.

Prosecutors added two lesser charges Friday alleging lewdness with a minor to the kidnapping, sexual assault with a minor, coercion and burglary charges that could put Alotaibi in prison for life if he is convicted.

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Find Ken Ritter at http://twitter.com/krttr

The U.S. is about halfway through this flu season, and "it's shaping up to be a worse-than-average season" and a bad one for the elderly, said Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention.

It's not too late to get a flu shot, and "if you have symptoms, please stay home from work, keep your children home from school" and don't spread the virus, he said.

New figures from the CDC show widespread flu activity in all states but Tennessee and Hawaii. Some parts of the country are seeing an increase in flu activity "while overall activity is beginning to go down," Frieden said. Flu activity is high in 30 states and New York City, up from 24 the previous week.

Nine more children or teens have died of the flu, bringing the nation's total this flu season to 29. That's close to the 34 pediatric deaths reported during all of the last flu season, although that one was unusually light. In a typical season, about 100 children die of the flu and officials said there is no way to know whether deaths this season will be higher or lower than usual.

The government doesn't keep a running tally of adult deaths from the flu, but estimates that it kills about 24,000 people most years.

So far, half of confirmed flu cases are in people 65 and older. Lab-confirmed flu hospitalizations totaled 19 for every 100,000 in the population, but 82 per 100,000 among those 65 and older, "which is really quite a high rate," Frieden said.

"We expect to see both the number and the rates of both hospitalizations and deaths rise further in the next week or so as the flu epidemic progresses,'" so prompt treatment is key to preventing deaths, he said.

About 90 percent of flu deaths are in the elderly; the very young and people with other health problems such as diabetes are also at higher risk.

If you're worried about how sick you are and are in one of these risk groups, see a doctor, Frieden urged. One third to one half of people are not getting prompt treatment with antiviral medicines, he said.

Two drugs Tamiflu and Relenza can cut the severity and risk of death from the flu but must be started within 48 hours of first symptoms to do much good. Tamiflu is available in a liquid form for use in children under 1, and pharmacists can reformulate capsules into a liquid if supplies are short in an area, said Dr. Margaret Hamburg, head of the Food and Drug Administration.

To help avoid a shortage, the FDA is letting Tamiflu's maker, Genentech, distribute 2 million additional doses of capsules that have an older version of package insert.

"It is fully approved, it is not outdated," just lacks information for pharmacists on how to mix it into a liquid if needed for young children, she said.

This year's flu season started about a month earlier than normal and the dominant flu strain is one that tends to make people sicker. Vaccinations are recommended for anyone 6 months or older. There's still plenty of vaccine an update shows that 145 million doses have been produced, "twice the supply that was available only several years ago," Hamburg said.

About 129 million doses have been distributed already, and a million doses are given each day, Frieden said. The vaccine is not perfect but "it's by far the best tool we have to prevent influenza," he said.

Carlos Maisonet, 73, got a flu shot this week at New York's Brooklyn Hospital Center at the urging of his wife, who was vaccinated in August.

"This is his first time getting the flu shot," said his wife, Zulma Ramos.

Last week, the CDC said the flu again surpassed an "epidemic" threshold, based on monitoring of deaths from flu and a frequent complication, pneumonia. The flu epidemic happens every year and officials say this year's vaccine is a good match for strains that are going around.

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Online:

Flu vaccine finder: http://www.flu.gov

CDC flu info: http://www.cdc.gov/flu/index.htm

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AP Photographer Bebeto Matthews in New York contributed to this report.

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Follow Marilynn Marchione's coverage at http://twitter.com/MMarchioneAP

Marquez's stunning sixth round knockout of Pacquiao, considered one of the all-time greats of the sport, in Las Vegas on Saturday has made the Mexican welterweight (55-6-1 40 knockouts) a hot commodity.

The 39-year-old has not ruled out a fifth bout against Pacquiao, with undefeated American light-welterweight Brandon Rios also a possibility, but John believes he should be next in line for a shot at the Mexican, possibly at lightweight.

"I will fight Marquez at any weight because it is big money," the 33-year-old was quoted as saying in Monday's Straits Times. "I am a much better boxer than him and I have more speed and skill."

The duo met in Indonesia in 2006 with John claiming a unanimous points decision victory to defend his WBA featherweight title, though Marquez was unhappy at being docked points in the late rounds for low blows.

John's Australian promoter, Angelo Hyder, told the newspaper the fight could happen in a neutral venue.

"Marquez and his team have always disputed the decision, even though all three judges gave it to Chris, and so boxing in a neutral place like Singapore could make the fight happen," he was quoted as saying.

"We will approach them and try and get the fight because this is unfinished business."

While John has long fought at featherweight (126 pounds), Marquez has been boxing in the welterweight and light welterweight divisions over the last couple of years.

The Mexican last boxed as low as lightweight (136 pounds) in a 2010 world title victory over Australian Michael Katsidis.

Marquez, who contemplated retirement before beating Pacquiao, looked extremely comfortable at 147 on Saturday.

"He is a massive puncher and knocked Manny Pacquiao clean out with one punch and it is my job to make sure I do not get hit with the same punch," John said.

"I want the fight and will win again."

John (48-0-2 22 knockouts) was named the WBA's fighter of the decade earlier this year but has long been criticised for not fighting more in the United States, the traditional home base of the sport where the likes of Marquez and Pacquiao have regularly fought.

The Indonesian's last two bouts have taken place at the Marina Bay Sands resort in Singapore, part of a five-fight series before retirement, John said previously. (Reporting by Patrick Johnston; Editing by Peter Rutherford)

Instead, the view out the windows of a vehicle traveling through hyperspace would be more like a centralized bright glow, calculations show.

The finding contradicts the familiar images of stretched out starlight streaking past the windows of the Millennium Falcon in "Star Wars" and the Starship Enterprise in "Star Trek." In those films and television series, as spaceships engageor hyperdrive and approach the , stars morph from points of light to long streaks that stretch out past the ship.

But passengers on the Millennium Falcon or the Enterprise actually wouldn't be able to see stars at all when traveling that fast, found a group of physics Masters students at England's University of Leicester. Rather, a phenomenon called the Doppler Effect, which affects the wavelength of radiation from moving sources, would cause stars' light to shift out of the visible spectrum and into the X-ray range, where human eyes wouldn't be able to see it, the students found. []

"The resultant effects we worked out were based on Einstein's theory of Special Relativity, so while we may not be used to them in our daily lives, Han Solo and his crew should certainly understand its implications," Leicester student Joshua Argyle said in a statement.

The Doppler Effect is the reason why an ambulance's siren sounds higher pitched when it's coming at you compared to when it's moving away the sound's frequency becomes higher, making its wavelength longer, and changing its pitch.

The same thing would happen to the light of stars when a spaceship began to move toward them at significant speed. And other light, such as the pervasive glow of the universe called the cosmic microwave background radiation, which is left over from the Big Bang, would be shifted out of the microwave range and into the visible spectrum, the students found.

"If theexisted and really could travel that fast, sunglasses would certainly be advisable," said research team member Riley Connors. "On top of this, the ship would need something to protect the crew from harmful X-ray radiation."

The increased X-ray radiation from shifted starlight would even push back on a spaceship traveling in hyperdrive, the team found, slowing down the vehicle with a pressure similar to the force felt at the bottom of the Pacific Ocean. In fact, such a spacecraft would need to carry extra energy reserves to counter this pressure and press ahead.

Whether the scientific reality of these effects will be taken into consideration on future Star Wars films is still an open question.

"Perhaps Disney should take the physical implications of such high speed travel into account in their forthcoming films," said team member Katie Dexter.

Connors, Dexter, Argyle, and fourth team member Cameron Scoular published their findings in this year's issue of the University of Leicester's Journal of Physics Special Topics.

You can follow SPACE.com assistant managing editor Clara Moskowitz on Twitter.Follow SPACE.com on Twitter. We're also on&.

The latest reference to Khamenei's declaration is seen as a bid to close the door on debates that Iran may have carried out atomic bomb trigger tests as inspectors from the U.N. atomic watchdog were on their way to Tehran for a new round of discussions.

Iran authorities have often cited Khamenei's religious edict, made more than seven years ago, in attempts to counter Western suspicion that Iran could be moving toward nuclear arms. But Iranian leaders now appear increasingly desperate to reopen talks with world powers as a possible way to ease sanctions.

Ministry spokesman Ramin Mehmanparast touched on a cultural rift between the Islamic Republic and the West, saying the United States and its allies don't understand the significance of the edict.

"There is nothing higher than the exalted supreme leader's fatwa to define the framework for our activities in the nuclear field," he told a press conference.

Mehmanparast could not be more definitive in dispelling suspicions that Iran may ultimately develop a nuclear weapon.

"We are the first country to call for a Middle East free of nuclear weapons," he said. When the highest jurist and authority in the country's leadership issues a fatwa, this will be binding for all of us to follow. So, this fatwa will be our top agenda."

Mehmanparast said Westerners "don't have an accurate understanding of Islamic beliefs and fatwas issued by great scholars," suggesting that the U.S. and its allies must take Khamenei's edit seriously.

To highlight its seriousness, he said Iran is willing to "register the fatwa as an international document."

Although Iran views Khamenei's 2005 fatwa as a binding declaration, the West and its allies have repeatedly accused Iran of using any tactic to prolong the standoff and possibly advance its nuclear capabilities.

The perception gap also strikes at the role of the supreme leader himself. The most ardent followers consider the post as divinely imbued and answerable only to God. For Iran's opponents, Khamenei is often seen as guiding a ruling system seeking to outwit the West and threaten Israel.

They want Iran to stop enriching uranium to a level that could be turned relatively quickly into the fissile core of nuclear arms. Iran denies such aspirations, insisting it is enriching only to make reactor fuel and to make isotopes for medical purposes.

Senior U.N. investigators trying for more than a year to restart a probe into Iran's alleged work on nuclear arms chose their words carefully Tuesday about hopes for success as they left for Tehran on a trip that sets the stage for separate talks between six world powers and the Islamic Republic.

Team leader Herman Nackaerts said the International Atomic Energy Agency hopes to "finalize the structured approach" that would outline what the agency can and cannot do in its investigation.

Yukiya Amano, the IAEA chief, has expressed doubt that Tuesday's trip would result in a deal, but Iran said it's optimistic.

"If there are any ambiguities or concerns, we are ready to clear these ambiguities. This can be done under a structured approach," he said.

Iranians say they have a bitter memory of allowing IAEA inspections and providing replies on a long list of queries over its nuclear program in the past decade. Now, Tehran says such queries should not be revived or remain open-ended once the IAEA has verified them.

Mehmanparast said Iran provided detailed explanations to IAEA questions on six outstanding issues in the past but instead of giving Iran a clean bill of health, the agency leveled new allegations on the basis of "alleged studies" provided by Iran's enemies.

Iran uses that term to refer to a list of questions including a dispute at Parchin, a military site southeast of Tehran, where the agency suspects Iran ran explosive tests needed to set off a nuclear charge.

Tehran has in the past allowed IAEA inspectors twice into Parchin but now it says any new agency investigation must be governed by an agreement that lays out the scope of such a probe.

"Obligations of the other party must be clearly specified. If a claim is to be raised on a spot in Iran every day and (the U.N. agency) seeks to visit our military facilities under such a pretext ... this issue will be unending," Mehmanparast said.

Iran says the agency's suspicions are based on forged intelligence from the United States, Israel and others, materials it has not been allowed to see.

Iranian leaders appear to be frustrated over the long investigations. Prominent lawmakers say Iran wants an end to the probe once and for all.

"We are interested to put an end to these ambiguities. We don't want a prolongation of this process," Alaeddin Boroujerdi, head of the parliament's security committee, said recently.

Iran is also linking its cooperation with the IAEA on Parchin to a commitment from the agency that Iran's nuclear dossier is referred back to Vienna from the U.N. Security Council.

Iran is under four sets of Security Council sanctions and stepped-up Western oil and banking sanctions over its refusal to halt uranium enrichment, a technology that can be used to produce nuclear fuel or materials that can be used for a warhead.

Tuesday's trip by the IAEA team comes as Iran and six world powers the United States, Russia, China, Britain, France and Germany prepare to meet, tentatively later this month.

The trip and the planned Iran talks are formally separate but both IAEA officials and diplomats involved in the talks privately acknowledge an informal link.

By compromising on the IAEA probe, Iran could argue that the onus was now on the six powers to show some flexibility, temper their demands, and roll back U.S. and European sanctions that have hit Iran's critical oil exports and blacklisted the country from international banking networks.

Mehmanparast made it clear Tuesday what Iran wants in return for cooperation with the IAEA: "In exchange for the easing of those ambiguities, our nuclear case should go back to its normal procedure and all the discussions raised about our nuclear case should be stopped."

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George Jahn in Vienna contributed to this report.