Iran appears to have "lost interest" in completing the nuclear power plant which Russia is helping it build at Bushehr, Russia's top nuclear official said Wednesday.

"I'm astonished. Maybe the Iranian leadership isn't completely informed, but there's an impression the Iranian side has lost interest in the construction" of the Bushehr nuclear power station, Sergei Kiriyenko, chief of Russia's federal nuclear energy agency, was quoted as saying by Interfax news agency.

"From mid-January, not a single kopeck has been paid" to complete the one-billion-dollar (760-million-euro) plant, which would be Iran's first, Kiriyenko told journalists during a visit in the Italian city of Bari.

The Bushehr plant was scheduled to be launched in the autumn but has been repeatedly delayed as Moscow and Tehran have argued over financing and technical difficulties.

Washington, which accuses Tehran of attempting to develop nuclear weapons under the guise of a civilian energy program, has urged Russia to delay the plant's completion.