Delegates from Iran, the U.S. Russia and France meeting at Vienna's International Centre on Monday to discuss whether Iran will farm out some of its uranium enrichment program to a foreign country. (Hans Punz/Associated Press)

Talks aimed at persuading Iran to hand over the further enrichment of its uranium to outside countries have bogged down on Tuesday over Iranian resistance to France's participation, diplomats said.

Representatives from Iran, the U.S., Russia and France are meeting in Vienna to discuss a plan aimed at resolving an impasse over Iran's nuclear program.

Iran has claimed its nuclear facilities are for energy purposes, but the international community has expressed concern they might be used to develop nuclear weapons.

Under the terms of the deal agreed to on Oct. 1 after talks in Geneva, a foreign country, likely Russia, would help enrich uranium for Iran and then send it to France for conversion into metal fuel rods to fuel a small research reactor in Tehran.

Iran has balked at shipping most of its low-enriched uranium abroad, saying it needs it for nuclear fuel. But on Tuesday the main issue was France's participation in the plans to send Iran's uranium abroad.

Sanctions limit nuclear trade

One diplomat, who spoke to the Associated Press on the condition of anonymity, said the talks could fail if the problem isn't addressed. Talks were delayed two hours while the participants worked on the issue.

Iran holds a 10 per cent share in a Eurodif nuclear plant in France and has been critical of the government of French President Nicolas Sarkozy for withholding enriched uranium from the plant.

France, however, is bound by UN sanctions levelled against Iran that ban trade in materials, equipment, goods and technology that could contribute to the nuclear program.

Iran is under three sets of sanctions for continuing its program and failing to allow UN inspectors to investigate its nuclear facilities, and Western powers had discussed a fourth set of sanctions after it was revealed in September that the country had begun work on a second uranium enrichment plant.

Iranian Foreign Minister Manouchehr Mottaki downplayed the problem.

"There are side issues ... with France," he told reporters from Tehran. "We will talk about it when time is right."

During the Geneva discussions, Iran agreed to allow inspectors to visit the second plant, raising hopes that a negotiated settlement could be reached.

Mohamed ElBaradei, who heads the UN's Atomic Energy Agency, had said on Monday that the first day of discussions had been productive.

Iran resisting calls to turn over uranium

The major issue of the talks is how much of Iran's estimated stockpile of low-enriched uranium it is willing to turn over as part of the agreement. The Geneva talks put the tentative quantity at 1,200 kilograms, or as much as 75 per cent of Iran's declared stockpile.

The agreement would be significant because 1,000 kilograms is the commonly accepted threshold of low-enriched uranium needed for production of weapons-grade uranium enriched to levels above 90 per cent.

Based on the Iranian stockpile, the U.S. has estimated Tehran could produce a nuclear weapon between 2010 and 2015.

Iran's state-run Press TV had cited unidentified officials in Tehran as saying the Islamic Republic would resist calls to turn over its low-enriched uranium and instead buy what it needed for the Tehran reactor abroad, a stance officials said could doom the talks.

With files from the Associated Press