The European Union called on the United States and Russia for support as it launched last-ditch efforts to persuade Iran to curtail its nuclear program on Friday before the issue is referred to the U.N. Security Council.

At a meeting of senior officials of the Group of Eight industrial powers in Washington, the EU sought support for a plan to offer Tehran economic and technological benefits if it halts all uranium enrichment activities that could enable it to build a bomb.

Senior Iranian nuclear negotiator Hassan Rohani is expected to visit Europe for talks in the next two weeks but the EU diplomats he is likely to meet with during his tour are not optimistic Tehran will comply with the plan, even though Iran is anxious not to be put in the dock at the Security Council.

Rohani would be told a suspension of enrichment-related activities would have to be clearly defined and verifiable before Nov. 25 when the International Atomic Energy Agency board meets in Vienna. A last-minute promise would not be enough to avoid the Security Council.

Diplomats fear Iran will miss last chance

"I fear Iran has moved towards a greater determination to continue its enrichment activities. It will be difficult to get them to say we completely stop," one senior EU diplomat told reporters after the meeting in Washington. Iranian leaders insist on their legal right to carry out nuclear fuel enrichment, rather than discussing whether it is really in their national interest to do so, he said.

The senior diplomat said the risk if Iran were hauled before the Security Council was that Tehran would retaliate by resuming enrichment and that each further step by the international community would prompt a move away from compliance. "There is a risk of negative escalation, reciprocating every measure," he said.

If Iran refuses to comply, the 25 EU member states would recommend the sending of the Iranian case to the Security Council when they meet with Mohammed el Baradei and his International Atomic Energy Agency board on Nov. 25. Diplomats predicted that EU leaders or foreign ministers might make a public statement to that effect in early November to build pressure.

Solana to offer incentives

EU foreign policy chief Javier Solana was charged with devising a package of "carrots and sticks" to encourage Iran to cooperate when he met with ministers earlier in the week. Among the "carrots" would be a commitment to resume stalled talks on an EU-Iran trade and aid agreement and some more specific offer of energy cooperation, including a willingness to supply peaceful nuclear technology and fuel, the sources said.

"The appearance of Solana is a new element," said a European diplomat in Vienna. "The EU three (Germany, France and Britain) has never been able to bring in the entire EU. Pulling everything together would be new." Imprecision in an agreement struck with Tehran by the three big EU powers -- Britain, France and Germany -- last October has led to a year of disputes.

EU hopes for US assistance and influence

EU officials acknowledge that Europe alone cannot offer Iran big enough incentives to abandon what it insists is peaceful nuclear research, without the prospect of the United States ending its isolation of the Islamic Republic.

The United States has so far publicly opposed offering any incentives to Iran, which President George W. Bush bracketed with Iraq and North Korea in 2002 as part of an "axis of evil."

Hawks in the Bush administration advocate isolating and punishing Iran, and some influential U.S. neo-conservatives argue for a policy of "regime change" in Tehran. Like North Korea, which may already have the bomb, Iran wants a guarantee that its regime is left alone, diplomats say.