"The Russians have been very supportive of what we have been trying to do in the IAEA," the official said, speaking on condition of anonymity.
"I think they, to some degree, have that religion as far as the dangers posed by Iran's nuclear programs, and they are working with us to try to get (Iran) to comply with the IAEA's demands."
International Atomic Energy Agency director Mohamed ElBaradei earlier told the Spanish newspaper El Pais that his agency would report at a November 20 meeting that Iran has failed to honor some international nuclear safeguards.
It was the first confirmation by the IAEA that new Iranian information, filed ahead of an October 31 deadline, showed Iranian failures in honoring nuclear safeguards agreements.
Tehran faces the possibility the IAEA will judge it to be in non-compliance with the nuclear Non-Proliferation Treaty and send the issue to the UN Security Council, which could then impose sanctions.
The United States accuses Iran of secretly working to manufacture highly enriched uranium, which can be used to make atomic bombs.
Russian support is key in that respect, because Moscow is building Iran's first nuclear power reactor at Bushehr, which has been fiercely criticized by Washington and Israel.
"I think that if Iran backslides on the commitments that it has now made, doesn't follow through, then the Russians, at the end of the day, however reluctant, would be prepared to cut the Bushehr project," the official said.