In an interview with AFP as European and Iranian negotiators held crucial talks in Geneva, Rice also left up in the air a US promise to lift objections to Tehran's applying for membership in the World Trade Organization.

"This is to support the (nuclear) negotiations, so we're going to see how the negotiations are going and we'll see whether the time is right," the chief US diplomat said.

Rice spoke as her counterparts from Britain, France and Germany met the top Iranian negotiator in Geneva in a final bid to stop Iran pressing ahead with activities that Washington fears could lead to a nuclear bomb.

Reports have circulated the Europeans were discussing a compromise with the Islamic Republic to allow it to go ahead with some nuclear activities, which the Iranians say are for strictly peaceful purposes.

But Rice insisted that an agreement struck in Paris last November to suspend work towards the enrichment of uranium "has to be observed and observed fully by the Iranians."

"This agreement has to end up ... in somehow a cessation of these activities, one that is a permanent cessation," she said.

"It also has to end up not leaving the Iranians with the sensitive technologies and activities associated with the nuclear fuel cycle."

The so-called EU-3 have been trying to wean Iran off its suspected nuclear weapons ambitions with economic and security incentives in an initiative now supported by a once-skeptical United States.

Iran's Foreign Minister Kamal Kharazi said Wednesday his country would discuss a plan under which it would resume preliminary conversion of uranium but move the ultra-sensitive process of enrichment to Russia.

Asked about the prospect, Rice said, "I'm not going to comment on proposals that are flying around, I don't want to get into speculations."

But she added, "We are in very close consultation and discussion with our European colleagues at several levels, and I think it would be a very good thing if the Iranians at this point continue the negotiations on the deal that is before them."

The United States has backed the European talks by offering to lift its objections to Iran's application for WTO membership and eventually helping it obtain spare parts for its airplanes.

But the Americans have made no secret of their desire to take Iran before the UN Security Council for possible sanctions if the European negotiations fail to rein in its nuclear program.

An Iranian negotiator complained Wednesday that US pressure was an obstacle to reaching an agreement with the EU ministers.

"The Europeans want to find a solution, but their room for manoeuvre is restricted because of their transatlantic political ties," Cyrus Nasseri told

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