"Bushehr is not apparently at the center of international concern because Bushehr is a project to produce nuclear energy," Mohamed ElBaradei, International Atomic Energy Agency (IAEA) chief, said after talks with Russian President Vladimir Putin.

"It's not something that is of any concern on our part," he told reporters at Putin's country residence outside Moscow. He said Bushehr was not mentioned in his hour-long talks with Putin and Russia's top atomic and security officials.

Washington, which says Iran is part of an "axis of evil" of states seeking weapons of mass destruction, has called on Russia to ditch the project. It also fears Iran would use Bushehr as a cover for the transfer of other sensitive nuclear technology.

Iran says it has no atomic weapons plans. Moscow denies any suggestion that Tehran could make a bomb on the basis of the technology to operate the power station.

A Moscow source involved in the Bushehr project said ElBaradei's support was crucial at a time when Washington seemed to be stepping up criticism of Iran's nuclear program.

"He publicly threw his weight behind Russia, and that's really important for us to keep the project rolling," the source said.

To allay U.S. concerns Iran could extract plutonium from Bushehr's spent nuclear fuel and make bombs, Russia has pledged to sign a deal with Iran to oblige it to return all fuel to Russia after a decade of use at Bushehr.

ElBaradei said the fuel "could be a concern" but praised Russia's resolve to get it back.

A Western diplomat who follows nuclear issues said it might not be wise for countries to cooperate in the nuclear field with Iran while it was not living up to its obligations.

"The more important problem at the moment is Iran's failure to satisfy obligations under the (Non-Proliferation Treaty) and obligations to other countries," the diplomat said.

He was referring to Iran's announcement last week that it was resuming production and testing of centrifuges, which can be used to enrich uranium, after promising France, Britain and Germany to suspend all uranium-enrichment related activities.

(Additional reporting by Louis Charbonneau)