The Kremlin on Tuesday declined to comment when asked if Russia was ready to take Iran's stocks of enriched uranium as part of a possible future nuclear deal with the United States.

The Guardian reported earlier on Tuesday that Tehran is expected to reject a U.S. proposal to transfer its stockpile of enriched uranium to a third country such as Russia as part of a future accord with Washington to scale back Iran's nuclear program.

Moscow, a party to Iran's 2015 nuclear pact which President Donald Trump scrapped during his first term in office, has supported Tehran's right to have a civilian nuclear program.

The U.S. says it fears Tehran is building a nuclear weapon, something Iran denies.