TEHRAN, 13 April 2006 — Russia and the European Union joined the United States yesterday in condemning Iran’s assertion that it had enriched uranium in defiance of a UN demand, but Moscow said force could not resolve the dispute.

President Mahmoud Ahmadinejad declared on Tuesday that Iran had enriched uranium for the first time and would now press ahead with industrial-scale enrichment.

His triumphant announcement keeps Iran on a collision course with the United Nations and with Western countries convinced that it is seeking nuclear weapons, not just fuel for power stations as it insists.

Denouncing Iran’s successful enrichment of uranium as unacceptable to the international community, US Secretary of State Conodoleezza Rice said yesterday the UN Security Council must consider “strong steps” to induce Tehran to change course.

Rice also telephoned Mohamed El-Baradei, the head of the International Atomic Energy Agency, to ask him to reinforce demands that Iran comply with its nonproliferation requirements when he holds talks in Tehran tomorrow.

While Rice took a strong line, she did not call for an emergency meeting of the council, saying it should consider action after receiving an IAEA report by April 28. She did not elaborate on what measures the United States would support, but economic and political sanctions are under consideration.

Russian Foreign Minister Sergei Lavrov said the use of force could not solve the standoff over Iran’s nuclear program, but he did not reiterate Moscow’s past opposition to sanctions.

“If such plans exist they will not be able to solve this problem. On the contrary they could create a dangerous explosive blaze in the Middle East, where there are already enough blazes,” he was quoted by Russian news agencies as saying.

US President George W. Bush this week dismissed media reports of plans for strikes on Iran as “wild speculation” and said force might not be needed to curb its nuclear ambitions. The Russian Foreign Ministry urged Tehran to stop all enrichment work, saying its proclaimed atomic advance ran counter to the decisions of the IAEA and the UN Security Council.

But a senior Iranian official ruled out any retreat. “Iran’s nuclear activities are like a waterfall which has begun to flow. It cannot be stopped,” said the official, who asked not to be named, referring to the Russian demand.

El-Baradei will visit Iran today to seek full Iranian cooperation with the Security Council and IAEA inquiries, a trip now clouded by Ahmadinejad’s speech.

The IAEA, whose inspectors are in Iran investigating nuclear sites, has made no comment on Iran’s statements. But an agency diplomat said: “The timing was strange but it may have been intended by them to improve their bargaining position.” The Security Council has told Iran to halt all sensitive atomic activities and on March 29 it asked the IAEA, the UN nuclear watchdog, to report on its compliance in 30 days.

Three European states behind a deal to suspend enrichment which broke down last year weighed in with criticism of Iran.

British Foreign Minister Jack Straw said the announcement was “deeply unhelpful” and undermined confidence. His German counterpart, Frank-Walter Steinmeier, said Iran was “going in precisely the wrong direction” for a return to negotiations.

French Foreign Minister Philippe Douste-Blazy said it was a worrying step and Iran should stop its “dangerous activities.”

The European Union voiced dismay. “This is regrettable,” said Emma Udwin, a spokeswoman for Benita Ferrero-Waldner, the EU commissioner for external relations.

The level of enrichment needed for nuclear bombs is far higher than the 3.5 percent Iran says it has reached.

It would take Iran about two decades to yield enough highly enriched uranium for one bomb with its current cascade of 164 centrifuges. Tehran says it wants to install 3,000 centrifuges, enough to produce material for a warhead in a year.

And Mohammad Saeedi, the deputy nuclear chief, said yesterday that Iran intends to move toward large-scale uranium enrichment involving 54,000 centrifuges, signaling the country’s resolve to expand the program.