Raisi said he had presented Moscow with draft documents on strategic cooperation that would cement joint collaboration for the next two decades.

"We in Iran have no limits for expanding ties with Russia," the Iranian leader said on his first state visit since taking office in August.

He said Tehran wanted to develop relations with Moscow that would "not be temporary, but permanent and strategic".

"Today's exceptional circumstances require significant synergy between our two countries against US unilateralism," he said in televised remarks.

Putin praised the countries' "close cooperation" on the international stage and said "it is very important for me to known your opinion on the Joint Comprehensive Plan of Action".

The 2015 accord between Iran and world powers -- the United States, France, Britain, Russia, China and Germany -- offered Tehran relief from crippling international sanctions in return for deep curbs on its nuclear programme.

But the unilateral US withdrawal from the agreement in 2018 under former president Donald Trump prompted Tehran to walk back on its commitments.

Talks to restore the accord began again last year but stopped in June, when Iran elected Raisi. They then resumed in November.

This is the ultraconservative president's most significant visit abroad since he took over in August from moderate Hassan Rouhani, who was the last Iranian president to visit Russia in March 2017.

Moscow and Tehran have strong political, economic and military ties, shared interests in Afghanistan, and are key allies of Syrian President Bashar al-Assad in his country's decade-long civil war.