While presenting a tough stance and defending Iran in Security Council diplomatic negotiations, Russia began yesterday to signal it was losing its patience with the Tehran mullahs. In Moscow, Foreign Minister Sergei Lavrov publicly said the Iranians are “no help” to allies who want to avoid confrontation while solving Iran’s nuclear crisis.

Mr. Lavrov’s outburst came as frustrated diplomats from the five major Security Council power brokers were unable to reach an agreement on how to handle Iran’s defiance. America and Europe want the council to deepen its involvement, including sanctions against Tehran if necessary, a move that is feared by China and Russia.

U.N. sources, who declined to be named due to the delicate negotiations, said an American-backed joint British-French proposal for a council statement met stiff resistance from the Russians and the Chinese. The five council members who have veto rights were said to have reached an “impasse.”

The permanent members, the P-5, are expected to attempt to reach an agreement this morning. The West-proposed statement, if accepted, would present Iran with a deadline by which it must freeze its uranium enrichment program and comply with other resolutions of the International Atomic Energy Agency.

But Washington is “not going to rest there if we can’t reach agreement,” America’s ambassador, John Bolton, said. If the P-5 fail to unite, several diplomats familiar with the negotiations said, the Europeans and Americans might force a vote in the full 15-member council on a resolution that would dare Russia and China to publicly contradict positions they already endorsed in Vienna last month during a meeting of the IAEA’s board of directors.

Despite its tough stance at Turtle Bay, “We are extremely disappointed with the way Iran is behaving in the course of these talks,” Mr. Lavrov said in Moscow. Iran is “absolutely no help to those who want to find peaceful ways to solve this problem.”

In Tehran, the spokesman for the supreme national council, Hossein Entezami, said that Moscow’s offer to create a joint Russian-Iranian uranium enrichment venture “should be reviewed.” A day earlier, however, a Foreign Ministry spokesman, Hamid Reza Asefi, said Russia’s offer was “no longer on our agenda.”

The Iranians “loved talking for the last four years and they’ll talk as long as they can, as they master the technical difficulties they’ve encountered in the uranium enrichment process,” Mr. Bolton told The New York Sun. “It’s no ‘stop the presses’ that the Iranians want to talk. Of course they do, to throw more sand in our eyes.”

Mr. Bolton called to “move expeditiously” toward an agreement that would deepen the council’s involvement. Such an agreement eluded negotiators yesterday, as Russian and Chinese diplomats argued against a mild-language proposed statement offered by France and Britain.

That statement would call on the IAEA director, Mohamed ElBaradei, to report “within 14 or 30 days” to the council on Iran’s compliance with past resolutions of the Vienna-based agency, including a demand for a freeze to all enrichment activity on Iranian soil, one diplomat said.

Despite yesterday’s disagreements among diplomats representing the five permanent members of the council, all seemed to be confident enough in the prospects of unity to schedule a briefing on their negotiations to the rest of the 15-member council. The briefing, planned for this afternoon at the French mission, was an indication of the prominent role France has assumed in the European-American alliance. The French position was in contrast to the rift among Europeans on the Security Council in the period before the 2003 Iraq war.