Russia will commence work on two nuclear power plant units in Iran next week.
A deal was brokered last year when state atomic agencies of the two countries signed an agreement, which involves construction of an overall eight nuclear reactors in Iran by Russia.
The first unit to be built will probably be an extension of the Bushehr nuclear power station, Iran’s first, which was completed by Russia in 2011.
Earlier this month, the UN nuclear watchdog closed a long-running investigation in Iran.
It issued a report that strongly suggested that the country was pursuing a coordinated programme 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 programme 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 major powers in July including Russia. In return, sanctions on the Iranian oil industry will be lifted.