Russia and Iran will this week sign agreements on the construction of new nuclear power units in Iran, Russian state news agency RIA quoted Iran's nuclear chief as saying.
Mohammad Eslami, who is also Iran's vice president, was speaking during a visit to Moscow.
Western governments accuse Tehran of failing to abide by a 2015 deal with world powers that aimed to prevent it from developing a nuclear weapon. Iran denies having any such intention and Russia says it supports Tehran's right to peaceful nuclear energy.
Putin offers Trump a one-year extension to nuclear arms pact
At the same time, Russian President Vladimir Putin offered his US counterpart Donald Trump a nuclear arms control deal on Monday that would extend the last treaty limiting both countries' nuclear weapons by one year while Moscow and Washington discuss what comes next.
Russia and the United States have by far the biggest nuclear arsenals in the world. The last remaining treaty between them that limits the numbers of these weapons is due to expire on February 5 next year.
The New START treaty covers strategic nuclear weapons - those designed by each side to hit the enemy's centres of military, economic and political power - and caps the number of deployed warheads at 1,550 on each side. Both are likely to breach that limit if the treaty is not extended or replaced.