A nuclear deal between world powers and Iran was "imminent," a senior adviser to Iran's supreme leader said at the Doha Forum in Qatar on Sunday.

"Yes, it's imminent. It depends on the political will of the United States," Sayyid Kamal Kharrazi, also a former Iranian foreign minister told the international conference.

However, U.S. Special Envoy for Iran Robert Malley voiced a contradictory message at the conference.

"I can't be confident it is imminent. A few months ago we thought we were pretty close as well," Malley said.

Kharrazi said it was vital for Washington to remove the foreign terrorist organization designation against Iran's elite Islamic Revolutionary Guard Corps (IRGC).

"IRGC is a national army and a national army being listed as a terrorist group certainly is not acceptable," he said.

Malley said the United States will maintain sanctions on IRGC.

The U.S. designated IRGC as a "foreign terrorist organization" under then President Donald Trump in April 2019. It came one year after Trump unilaterally withdrew the United States from the 2015 nuclear deal, known formally as the Joint Comprehensive Plan of Action (JCPOA).

Kharrazi also said Iran wanted guarantees that the United States would not withdraw again from the deal. Malley said there could be no guarantee after President Joe Biden's term ends.

Iran has been engaged in negotiations to revive the JCPOA with Britain, China, France, Germany and Russia directly and the United States indirectly since April 2021.

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(With input from Reuters, AFP)

(Cover: The flags of Iran and the U.S. are seen printed on paper. /Reuters)