Washington announced new sanctions on Thursday against the Atomic Energy Organisation of Iran and its head Ali Akbar Salehi.

Brian Hook, the US pointman on Iran, accused them of playing "a big role in Iran breaching its key nuclear commitments" and exceeding "the limits on its uranium stockpile and enrichment levels".

In a statement, Mousavi said "Mr Salehi is an eminent scientific and political figure" and sanctions against him showed the "despair" of the United States.

The sanctions would have "no impact on the progress of the peaceful nuclear programme of the Islamic republic of Iran," Mousavi added.

Salehi holds a doctorate of nuclear engineering from the Massachusetts Institute of Technology in the United States and was minister of foreign affairs from 2010 to 2013 before becoming Iran's atomic energy chief.

Since May 2019, Iran has progressively scaled back some commitments under the 2015 nuclear deal, in response to Washington's 2018 unilateral withdrawal from the agreement and decision to reimpose sanctions on Tehran.

The government of US President Donald Trump accuses Iran of attempting to acquire nuclear weapons, something Tehran denies.