EU-mediated negotiations began in Vienna in April aimed at reviving a 2015 nuclear agreement between Tehran and world powers -- an accord left hanging by a thread after former US president Donald Trump unilaterally withdrew in 2018 and ramped up sanctions.

The discussions, which involve the remaining parties seeking to persuade Washington to rejoin the deal and Iran to return to its nuclear commitments, have been stalled since June, when ultraconservative Ebrahim Raisi was elected as Iran's president.

An EU statement said Borrell "underlined once again the great importance of a quick resumption of the Vienna talks" at a meeting Tuesday with Iran's new top diplomat Hossein Amir-Abdollahian on the sidelines of the United Nations General Assembly.

"The Iranian Foreign Minister assured of the willingness to resume negotiations at an early date," the statement said.

Raisi voiced support Tuesday in his international debut for reviving the nuclear accord, even as he berated the United States.

"The Islamic Republic considers useful talks whose ultimate outcome is the lifting of all oppressive sanctions," Raisi said in a recorded speech to the UN.

Iranian foreign ministry spokesman Saeed Khatibzadeh said he expected a resumption of the talks "in the coming weeks", without giving an exact date.

The 2015 nuclear agreement offered Iran a reduction of UN sanctions in return for strict limits on its nuclear programme, but Tehran has progressively stepped away from its commitments in the wake of Trump's withdrawal and imposition of sanctions.

Trump's successor Joe Biden has signalled a willingness to return to the deal, which was negotiated when he was Barack Obama's vice-president and under Iran's moderate President Hassan Rouhani.

Hopes of a revitalised deal were kept alive earlier this month by Iran agreeing with the UN nuclear agency on a new compromise regarding surveillance of its nuclear sites.