Diplomats said the EU's 25 foreign ministers were due to discuss possible incremental measures targeted initially at individuals and materials involved in Iranian uranium enrichment activities, which the West suspects is aimed at making a bomb.

"The most important thing is to have a united response as we showed with North Korea. We must show Iran that the international community is completely determined to remain united," European External Relations Commissioner Benita Ferrero-Waldner told reporters.

"We have shown great patience ... We offered a very attractive package which could be beneficial for Iran, but up to now we have not received an acceptance," she said.

Spanish Secretary of State for European Affairs Alberto Navarro said sanctions would be gradual because Europe, unlike the United States, needed Iran as an oil supplier.

EU foreign policy chief Javier Solana, who wrangled for four months with Iranian national security chief Ali Larijani in a vain effort to persuade Tehran to suspend its most sensitive nuclear work, said the door to talks would remain open.

"I think there is always hope, and I would like it to be possible to start again, but it is up to Iran now to accept the conditions to start real negotiations," he said.

After the failure of the EU diplomatic effort, the ministers will say that the Iranian file must return to the U.N. Security Council, according to a draft statement.

The statement will express deep concern that Iran has not yet suspended enrichment activities and say the EU has no choice but to support talks in the United Nations on measures on the basis of resolution 1696, but that the door remains open to negotiations.

Security Council resolution 1696 had told Iran to suspend enrichment by August 31 or face sanctions.

The six major powers that backed the incentives package that Solana delivered to Iran -- the United States, Russia, China, Britain, France and Germany -- are set to start consultations at the United Nations on Wednesday on a sanctions resolution, diplomats said.

Moscow and Beijing have so far been extremely reticent about any sanctions, but a European diplomat said they had accepted the principle of an incremental approach raising pressure.