China, Russia, France, the United States, Germany, and Britain expressed "serious concerns" about Iran's resumption of small-scale uranium enrichment, Britain's Foreign Office said.
The powers stopped short of referring the issue to the U.N. Security Council, which could impose sanctions, instead calling for an emergency board meeting of the International Atomic Energy on Feb. 2-3 to discuss the issue. The 35-nation IAEA board could itself refer the issue to the Security Council.
The stepped up diplomatic activity came nearly a week after Iran removed U.N. seals at its main uranium enrichment plant and resumed research on nuclear fuel after a two-year hiatus. CBS News correspondent Richard Roth reports Iran's actions have pushed even its allies to have second thoughts about the country's nuclear ambitions, but there's no clear agreement on how to thwart them.
With a billion-dollar stake in Iran's atomic energy building program, Russia is eager to diffuse the crisis. So is China, Roth reports, which buys 300,000 barrels of Iranian oil a day.
The move alarmed the West, which fears Iran intends to build an atomic bomb. Iran claims its program is peaceful, intended only to produce electricity and it has threatened to end all cooperation the U.N. nuclear watchdog if it is brought before the Security Council.
U.S. Secretary of State Condoleezza Rice said Sunday that she wants a vote as soon as possible on whether to refer Iran to the council and is working to line up support.
"We've got to finally demonstrate to Iran that it can't with impunity just cast aside the just demands of the international community," Rice said while traveling in Africa.
The Russian president suggested there might still be hope of avoiding that path, saying Iran has not ruled out conducting its uranium enrichment in Russia, which would allow for close oversight.
In Moscow, Putin said the Iranians had indicated "they did not exclude the implementation of our proposal."
"In any case, it's necessary to work carefully and avoid any erroneous moves," he added.
Iran's ambassador to Moscow praised the idea.
"This is a good initiative to resolve the situation. We believe that Iran and Russia should find a way out of this jointly," Gholamreza Ansari said in comments translated into Russian and shown on state Channel One television.
The U.S. and the Europeans need support from Russia and China for referral because they have veto power in the Security Council.
Russia and China, which have close commercial ties with Iran, have resisted referral but also have shown increasing impatience with Tehran's defiance.
The European Union's foreign policy chief, Javier Solana, said he believed the two would eventually agree to refer Iran to the Security Council.
"I am confident. Otherwise, I will not be working as I am working," Solana said after meeting U.N. Secretary-General Kofi Annan.
A spokesman for Britain's Foreign Office, speaking on condition of anonymity in keeping with government policy, said representatives of the six nations who met for seven hours in London agreed "on the importance of Iran returning to the full suspension and negotiating process."
Putin said his proposal did not mean Russia's strategy differed from the one the Western powers are pursuing.
"Russia, Germany, our European partners and the United States have very close positions on the Iranian problem," he said after meeting with German Chancellor Angela Merkel.
China made no comment after the talks in London, but took a cautious tone earlier Monday.
"All relevant sides should remain restrained and stick to solving the Iranian nuclear issue through negotiations," the Foreign Ministry in Beijing said in a statement.
British Foreign Secretary Jack Straw, who was not at the meeting, said after it ended that London also wanted Iran to return to talks.
"What we hope is that as a result of this and other diplomatic pressure is that the Iranians will come back to the negotiating table ... and will recognize the good intent of the European three," he told Channel 4 news, referring to Britain, France and Germany, which negotiated with Tehran on behalf of the European Union for 2½ tense years.
Straw said the "onus is on Iran" to prove its program is peaceful. He said the international community's confidence had been "sorely undermined by a history of concealment and deception" by the clerical regime.
In a related development, Iranian state radio reported Monday that the country had allocated the equivalent of $215 million for the construction of what would be its second and third nuclear power plants.
Economic sanctions targeting Iran's oil and gas exports are thought unlikely. Iran is OPEC's second-largest producer and preventing it from doing business could disrupt the world's energy markets.
Russian experts also are helping build a nuclear reactor at Bushehr in Iran. But Moscow has shown growing impatience with Tehran for not accepting its proposal to supply nuclear fuel for Iranian power stations.
Russian Foreign Minister Sergey Lavrov said last week that the Kremlin has not ruled out backing Iran's referral to the Security Council, although it said previously it saw no need for such action.