Iranian negotiators Javad Vaeidi and Mohammad Saeedi were "flying from Vienna to Russia to persuade the Russians to finish building the Bushehr nuclear (power) reactor," said a diplomat who asked not to be named due to the confidential nature of the information.

The two Iranians had agreed Tuesday in Vienna to allow inspectors from the UN watchdog International Atomic Energy Agency (IAEA) to visit next week a heavy-water reactor being built in Arak and which is a proliferation concern since it will be able to produce plutonium, a potential atom-bomb material.

In Bushehr, on the other hand, Russia has been building a power reactor which is deemed to be proliferation safe, even though the United States is still concerned.

Construction stalled earlier this year over charges that Iran is not paying its bills for the Bushehr project.

There are also hints that Russia is slowing down work at Bushehr in reaction to the crisis caused by US claims that Iran is using what Tehran says is a civilian nuclear power program as a cover for the secret development of nuclear weapons.

The United Nations Security Council has imposed two rounds of sanctions on Iran to get it to suspend enrichment of uranium, like plutonium a potential material for atom bombs, and cooperate with an over four-year-old IAEA investigation.

But Iran is defying UN demands by continuing to enrich uranium and is threatened with a third round of sanctions.

Despite this, Vaeidi, Iran's deputy national security chief, and Saeedi, the deputy head of Iran's atomic energy agency, are set to tell the Russians that Iran is "cooperating with the IAEA and so Russia should move ahead on Bushehr, including starting delivery of nuclear fuel, and be firm against (new UN) sanctions," the diplomat said.

A second diplomat said the Iranians were continuing their diplomacy at a time when the six world powers -- Britain, China, France, Germany, Russia and the United States -- negotiating to win guarantees that Iran does not seek nuclear weapons, are split.

The diplomat said that the United States is yielding to Russian demands to hold off new UN sanctions against Iran while Tehran works on resolving with the IAEA questions about possible military uses of its nuclear work.

But the United States is insisting that Iran suspend all uranium-enrichment activities before multilateral talks can begin and is stopping EU foreign policy chief Javier Solana from holding further preparatory meetings with Iranian nuclear negotiator Ali Larijani.

The diplomat said Solana had been given this message by US Secretary of State Condoleezza Rice but this report could not be immediately confirmed.

The Iranians, said the diplomat, are in a bind since they "need some diplomatic progress as they have agreed to cooperation measures with the IAEA."

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