The EU warning came as Iranian negotiators headed to Europe for talks amid warnings that the meetings could be the last chance for the two sides to reach a deal on the Islamic republic's nuclear programme.

British Foreign Secretary Jack Straw, who will represent the EU along with his French and German counterparts in Geneva Wednesday, conceded he expected the meeting to be "tough."

The so-called EU-3 has warned that Iran could be referred to the UN Security Council if it reneges on a commitment made last November to suspect uranium enrichment activities.

"The issue before us will be to ensure that both sides stick by the agreements which we have already entered into," Straw said, referring to pledges to suspend key nuclear enrichment activities made in November.

Of the crisis talks he said: "I think they will be tough, but I think very much they will be successful."

As if on cue, a senior Iranian official said the negotiations were likely to be the last chance for the two sides.

"We would reach the conclusion that we haven't got along with them," if they fail, Ali Agha Mohammadi, the spokesman for Iran's Supreme National Security Council, told the student news agency ISNA.

He said the Iranians might not even travel to Geneva if no satisfactory offer was made during talks between experts in Brussels, scheduled for Tuesday.

Whether it was brinkmanship, rhetoric for public consumption ahead of next month's presidential election or a statement of fact, Solana refused to be drawn and said only that he was hopeful.

"I would prefer not to develop further at this point in time," he said. "I hope that the meeting will take place in Geneva."

Iran is suspected by the United States of wanting to build atomic weapons.

But the Islamic republic insists it has the right to master the full nuclear fuel cycle, including enriching uranium, as a signatory of the nuclear Non-Proliferation Treaty (NPT) and that it only wants to generate electricity.

Iran agreed in November not to resume uranium conversion, a precursor to the ultra-sensitive enrichment process which has prompted fears of a secret weapons programme, but has indicated it may end that suspension.

The EU's Luxembourg presidency meanwhile lamented Monday the decision by Iran's election watchdog to eliminate many pro-reform candidates for June presidential polls.

The Guardians Council, an unelected watchdog body that vets all candidates for public office, announced on Sunday that just six men out of 1,014 would-be candidates could stand to succeed incumbent reformist President Mohammad Khatami.

"We were very disappointed by the decision of the Guardians Council not to authorize many candidates for the elections, particularly those who were reformists," said Luxembourg Foreign Minister Jean Asselborn.

EU foreign ministers all agreed that Iran must meet its November commitments, he said.

"The commitments cannot be circumvented. This is very important for further relations between the EU and Iran," he added.

Straw declined to be drawn on what proposals the EU side would make, though it is believed to be ready to compromise on fuel supply for Iran's reactors and to offer trade incentives.

"The Iranians are tough to negotiate with, but so far the Iranians have accepted, as we (have), that it is in the interest of Iran, Europe and the international community that we should reach agreement," Straw said.

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