The US has during latest indirect negotiations accused Iran of raising issues "wholly unrelated" to the nuclear deal -- an apparent reference to a demand by Tehran that the US remove its Islamic Revolutionary Guards Corp from a terror blacklist.

"We have no requirement which goes beyond the nuclear agreement -- contrary to certain claims by the American party in the media," Foreign Minister Hossein Amir-Abdollahian told reporters in Tehran.

"Our request is part of the 2015 agreement," he added, appearing alongside his Qatari counterpart Sheikh Mohammed bin Abdulrahman Al-Thani.

The US walked out of the Iran nuclear deal in 2018 under then president Donald Trump, who proceeded to reimpose biting sanctions on Tehran, prompting the latter to step away from many of the nuclear commitments it made under the accord.

Iran has held direct talks with remaining parties to the deal -- and indirect talks with the US -- since last April in a bid to restore the deal, but those negotiations have been at an impasse since March.

Qatar last week hosted indirect talks in Doha in a bid to get the Vienna process back on track, but those discussions broke up after two days without any breakthrough.

"During the recent talks in Doha, one of the main questions we focused on was an effective guarantee from Washington assuring us of economic advantages linked to the agreement," Amir-Abdollahian said.

"The United States must commit to Iran being able to capitalise on the full benefits of the 2015 deal. So far, the US side has not been able to assure us" of that, he added.