"We made very good progress and entered into the elements of an agreement very seriously, both in the nuclear field and in the sanctions field," Araghchi told state TV after the talks in Geneva ended.

He said the Iranian delegation has "very clearly stated our demands", without elaborating.

Thursday's talks were the latest since negotiations began earlier this month against the backdrop of a heavy US military build-up in the region and with President Donald Trump repeatedly threatening strikes should talks fail.

During the interview, Araghchi said there was "evident seriousness" on both sides to reach a negotiated solution.

He said technical teams will hold discussions at the International Atomic Energy Agency in Vienna on Monday, and with the help of the agency's experts.

Beyond the technical talks, Iran and the US will hold another round of talks in "perhaps less than a week", he added.

"There are a series of tasks that both sides must do, a number of documents that must be prepared and a number of consultations that must be held in the capitals, and after that we will have the next meeting," he said.

Iran and Washington held five rounds of nuclear talks last year which collapsed following Israel's attack on Iran in June, which triggered a 12-day war.

That war saw the United States briefly join Israel with strikes on key Iranian nuclear sites.