Iran today repeated it would shortly resume sensitive nuclear work that could be used to make atomic arms.
In a deal with Britain, Germany and France last November Tehran agreed to suspend all nuclear fuel-related activities while both sides tried to negotiate a long-term solution regarding Iran's atomic ambitions.
The EU trio have warned Iran, which says its nuclear programme will never be used to make bombs, that they would back US calls to send Iran's case to the Security Council for possible sanctions if it resumed sensitive nuclear work.
Mohamed ElBaradei, head of the UN's nuclear watchdog, also urged Iran at a conference on nuclear proliferation in New York on Monday, not to "take a unilateral decision to initiate any activities that are currently suspended".
But Tehran, unhappy with the slow pace of its talks with the EU trio, said it was sticking by its decision to resume some enrichment-related work. "We will definitely restart some activities," Foreign Ministry spokesman Hamid Reza Asefi told a weekly news conference.
Iranian officials have suggested Iran will probably resume work at the Isfahan Uranium Conversion Facility, where uranium is processed into uranium hexafluoride gas. It would, however, maintain its freeze on actual enrichment of that gas, a process which can be used to make bomb-grade material.
"Right now the issue of resuming enrichment is not on the table. We don't want to do that now," Mr Asefi said. But he said Iran had warned that even that suspension was not indefinite.
Tehran is betting that a resumption of uranium processing, but not enrichment itself, will strengthen its bargaining position without provoking the EU trio to back Washington's call for Security Council referral, diplomats said.