Russia says Iran's Bushehr nuclear power plant will operate at its capacity in the next few weeks.
The first reactor at Bushehr went into operation earlier this week, but the plant is still running tests of control and protection systems.
The Bushehr plant is part of Iran's controversial civil nuclear energy program but because Tehran is obligated to return spent fuel from the plant to Russia, it is not considered a proliferation risk.
The United States and some of its allies believe the Bushehr plant is part of an Iranian attempt to develop nuclear weapons. Iran denies the accusation.
Russian deputy foreign minister Sergei Ryabkov told the RIA Novosti news agency on Thursday that Bushehr will become fully operational "in the coming weeks" but declined to provide a more accurate timeline.