Russia will start constructing two nuclear reactors in Iran next week, the spokesman for the Iranian atomic agency said today.

It comes a year after Tehran signed a contract with Moscow to build two reactors at the existing Russian-built Bushehr power plant in southern Iran.

Work on the two reactors "will commence next week," the state television website quoted Behrouz Kamalvandi as saying. 

A series of agreements signed between the two countries last year foresees eventually increasing the total number of Russian-built reactors in the country to nine.

The start of construction follows a historic deal between Iran and world powers in July that ends a decade-long standoff over Tehran's nuclear programme.

The accord does not limit Iran's development of civilian nuclear sites.