At an EU meeting in Luxembourg Tuesday, Javier Solana, the bloc's foreign policy chief, also welcomed the agreement but said he did not think that it required any great adjustments.

"I would hope to have contact tomorrow, probably telephonically. We'll see how things can develop from here till the end of the month," Solana told reporters after talks with European foreign ministers.

Since 2006 Solana has been negotiating on behalf of Britain, China, France, Russia, the United States plus Germany to try to persuade Iran to enter talks on suspending enrichment work in exchange for political and economic benefits.

Uranium enrichment is required to produce fuel for a nuclear reactor, but at highly refined levels can be used to make the core of an atomic bomb, which many in the West fear Iran is trying to covertly build.

France has said the new deal calls for Tehran to hand over 1,200 kilogrammes of 3.5 percent enriched uranium to Russia for refining up to 20 percent purity so it can fuel a Tehran research reactor which makes medical isotopes.

Earlier, state-owned Arabic language Al-Alam TV channel, quoting a source close to Tehran's nuclear negotiating team, said Iran will accept the broad framework of the deal, but wants very important changes in it.

"The deal was a good deal and I don't think this requires fundamental changes," said Solana, but added that "it's very difficult to know what it means; important changes."

French Foreign Minister Bernard Kouchner, meanwhile, said the delay was not a good sign and warned the Islamic Republic -- renowned for its negotiating brinksmanship -- that time is running out.

"It's not a good sign, whereas it was so simple" to accept the proposal put to Iran by the major powers, including France, who are negotiating over its nuclear drive. "I don't think this is very encouraging," he said.

Earlier he told reporters: "Iran is wasting time because now is the time for talking."

"One day, it will be too late," he added.

Moscow has called for patience within the international community, but Kouchner's is wearing thin.

"We have been waiting for light at the end of the tunnel for almost three years. We will wait until we decide that enough is enough and that the process is exhausted," he said.

Tehran has defied five UN security council resolutions on its controversial nuclear programme, including three with sanctions attached.

"Even if it is clear that talks cannot go on forever, no one wants to give Iran a deadline that is too precise, because otherwise Tehran could just play with it," said an EU diplomat.