Fischer told reporters that the basis for any talks must remain the suspension of operations at the uranium conversion facility at Isfahan, which Tehran announced Monday it was resuming.

He said Germany, Britain and France, which have led the EU negotiations with Iran, were doing everything in their power "to avert a negative development with disastrous consequences".

Mohammad Saidi, vice president of Iran's Atomic Energy Agency, said earlier Monday in Isfahan that Iran has "resumed the conversion of uranium under the supervision of the IAEA," the United Nations' nuclear watchdog.

The move, which risks seeing Iran referred to the UN Security Council for possible sanctions, comes after Iran rejected as "unacceptable" a package of EU proposals aimed at guaranteeing that it was not trying to build a nuclear weapon.

German Chancellor Gerhard Schroeder said Saturday that he was "very worried by the path of confrontation that Iran seems to have chosen" and said it could lead to a move for UN sanctions.

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