Nuclear talks between Iran and world powers were held up Tuesday after Iran said it did not want France to be part of any deal on uranium enrichment.

The International Atomic Energy Agency (IAEA) did not say however why the second day of talks had been delayed, even though all the delegations had gathered at the UN watchdog's headquarters.

The new twist came after Iranian Foreign Minister Manouchehr Mottaki said in Tehran that France was not needed at the talks, which also involve Russia, the United States and IAEA officials.

Iran has told the IAEA it needs fuel for a research reactor and a proposal has been made for Russia and France to enrich Iranian uranium. Western powers want greater control of Iran's uranium which they fear is being used to build a nuclear bomb.

"The agency contacted some countries and the United States and Russia accepted to participate in the negotiations to supply the fuel," Mottaki said.

"The negotiations will be conducted with these two countries in the presence of the agency. We do not need a lot of fuel and we do not need the presence of many countries. There is no need for France to be present.

Delegations from France, Iran, Russia, the United States and the IAEA had gathered in the room at the agency headquarters before deciding to delay the start.

The teams from Tehran and Paris appeared to make a point of leaving the room together. And diplomats played down suggestions that the delay was over the foreign minister's comments.

"It's just regular diplomacy as delegations try to advance the issues," one diplomat told AFP on condition of anonymity.

"It is not about the continued French participation but rather about how to best structure a deal so that everyone can be satisfied. Even beyond the politics this is complicated," the diplomat said.

On Monday, Iranian media said Tehran did not want France at the negotiating table, because it had not fulfilled "previous obligations regarding nuclear cooperation with Iran."

State-owned Al-Alam television channel quoted an informed source close to Tehran's negotiating team in Vienna as saying France "does not have an acceptable record and since it also obstructed the negotiations between Iran and the IAEA."

In Vienna, diplomats taking part in the talks insisted that France was still on board. "France remains at the talks," one diplomat told AFP, speaking on condition of anonymity.

On Monday, IAEA chief Mohamed ElBaradei had said the negotiations had gotten off to a "constructive" start.

Iran has 1,500 kilogrammes of low-enriched uranium at its plant in Natanz, in defiance of three rounds of UN sanctions to back demands that it halt all enrichment activity.

But it needs a higher level of enrichment to run a research reactor in Tehran, which makes isotopes needed for medical use such as cancer treatment.

Western powers suspect Iran has embarked on research to build a nuclear bomb. Iran has denied the claims but has been accused by the IAEA of not cooperating with IAEA efforts to determine whether its atomic programme is peaceful.