A US official, speaking on condition of anonymity, confirmed to AFP that the two men, who have been Trump's lead Iran negotiators, would represent Washington for the talks.

Iran's Foreign Minister Abbas Araghchi will represent Tehran in the negotiations, his ministry reported earlier. He will also meet with his Swiss and Omani counterparts and the head of the International Atomic Energy Agency.

Tehran and Washington restarted negotiations in Muscat on February 6, months after previous talks collapsed when Israel launched an unprecedented bombing campaign against Iran last June that started a 12-day war.

The United States joined that war, carrying out strikes on Iranian nuclear facilities.

Iran said the Geneva talks would be "indirect," as the previous round in Oman had been.

The latest talks came with Washington having threatened Tehran with military action and deploying an aircraft carrier group to the region following Iran's deadly crackdown on anti-government protests last month.

After the Iran talks, Witkoff and Kushner are expected to participate in US-brokered talks between Russia and Ukraine in Geneva.