Russia will begin building two nuclear power plant units in Iran next week, Mehr news agency quoted an Iranian nuclear official as saying, under a deal signed in Moscow last year between subsidiaries of the two countries' state atomic agencies.
The Mehr report did not elaborate but the comments by Behrouz Kamalvandi, spokesman for the Atomic Energy Organization of Iran, appeared to be referring to extension of the Bushehr nuclear power station, designed and built by Russia.
Iran already runs one Russian-built nuclear reactor at Bushehr, its first. Russia signed a deal with Iran in November last year to build up to eight more reactors in the country.
The U.N. nuclear watchdog earlier this month closed a long-running investigation of Iran and issued a report strongly suggesting it pursued a coordinated program to devise a nuclear bomb up until 2003 but that there was no credible sign of bomb-related research and development activity beyond 2009.
The Bushehr plant itself was never considered by diplomats and experts to be a serious nuclear proliferation risk.
Other aspects of Iran's nuclear program seen as having potential to develop weapons, such as its uranium enrichment activity and a heavy water reactor, will be curbed under a deal Iran reached with big powers in July including Russia.
The Islamic Republic will see international sanctions on its oil-based economy lifted in return.