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.
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Construction of the two reactors will be bankrolled by Iran, Sergei Kiriyenko, head of Russia's state nuclear company Rosatom, said last year.
Iran plans to build 20 more nuclear plants in the future, including four in Bushehr, to decrease its dependence on oil and gas.
Russia backed Iran during two years of nuclear negotiations with six world powers.
The two countries have recently allied to prop up Syrian President Bashar al-Assad against opposition and jihadist groups, mainly the Islamic State organisation.