"Iran is wasting time because now is the time for talking," Kouchner said on arrival in Luxembourg for a meeting of European Union foreign ministers. "One day, it will be too late," he added.

"The Americans, through (Barack) Obama's energy, have breathed new life into the necessity for dialogue but that cannot last forever.

"We need answers. We have all shown a great deal of patience."

Foreign Minister Mottaki on Monday said Iran was mulling a United Nations-brokered deal which envisages sending Tehran's low-enriched uranium (LEU) abroad to be converted into nuclear fuel, as a UN team ended its inspection of a newly revealed atomic plant.

Iran's Fars news agency on Tuesday reported that Tehran will deliver its response within two days.

"An informed source told Fars that the Islamic Republic of Iran within the next two days will respond to the draft of providing fuel for the Tehran reactor," the report said.

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

"(Manouchehr) Mottaki makes these declarations, then he reformulates them," the Frenchman went on. "They rarely provoke enthusiasm, they are rarely very positive.

"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."

Enrichment of uranium is the most controversial aspect of Tehran's nuclear programme since it can be used both to generate electricity -- as Tehran says it is doing -- or to make the fissile core of an atom bomb.

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," added another European diplomat.

"I don't want to answer what is going to happen, but I hope they say yes," underlined the EU's foreign policy supremo Javier Solana. "I hope that by the end of the month we'll know something."