Russia urged Iran to cooperate with the international community Thursday, as the United Nations’ atomic agency warned that it had hit a “dead end” over whether Tehran is developing a nuclear weapon.

Deputy Foreign Minister Sergei Ryabkov discussed the nuclear issue in Moscow with Ambassador Mahmoud Reza Sajjadi at the Iranian diplomat’s request, the Foreign Ministry said on its web site.

“The Russian side especially underscored the necessity to observe the agreements in principle reached in talks in Geneva,” the statement said. Iran held talks with the five permanent members of the UN Security Council — the United States, Russia, China, France and Britain — and Germany on Oct. 1.

Mohamed ElBaradei, the outgoing head of the International Atomic Energy Agency, said Thursday in Vienna that his organization had “effectively reached a dead end” with Iran. Tensions are increasing as Washington pushes for harsher sanctions if Iran does not prove that its nuclear program has exclusively peaceful aims.

The unusually blunt comments appeared to be a reflection of frustration, four days before ElBaradei ends his 12-year tenure at the IAEA.

World powers are now demanding that Iran immediately mothball a uranium enrichment site it hid for years, heightening fears that it is planning to build atom bombs, in a resolution to be voted on by IAEA governors.

Diplomats forecast majority approval for the resolution in a vote in Vienna by IAEA’s 35-nation governing board later Thursday or Friday in what would be its first action against Iran in almost four years.

The move reflects dismay over the country’s September disclosure of a second enrichment site it had been building clandestinely for two years, and frustration at Iran’s holdup of an IAEA-brokered plan to give it fuel for its nuclear medical program if it parts with enriched uranium that could be used in weapons. That deal would see Tehran send 75 percent of its low-enriched uranium to Russia and France.

The last IAEA board resolution passed against Iran was in February 2006, when governors referred Tehran’s case to the Security Council over its refusal to suspend enrichment and open up completely to IAEA inspections.

The new measure’s sponsors were the United States, Britain, France, Germany, Russia and China.

Russian and Chinese support was significant, and expected to secure rare developing-nation votes against Iran, since the two have often blocked a tough united front against Iran in global security bodies and avoided direct criticism of Tehran.

Vienna diplomats said China was won over at the last minute by strong Western lobbying. It was not clear how.

Russia, which is building Iran’s first nuclear power plant, has sent contradictory messages over the need for new sanctions, with President Dmitry Medvedev indicating a willingness to punish Iran and Prime Minister Vladimir Putin holding off from threats.

Energy Minister Sergei Shmatko is due to travel to Iran on Sunday and Monday.

(Bloomberg, Reuters, AP)