The talks, brokered by the Europeans, seek the return of the United States to the 2015 agreement trashed by former president Donald Trump -- as well as Iran's return to full compliance.

"We are reviewing the Vienna negotiations files currently and very soon Iran's negotiations with the four plus one countries will recommence," Hossein Amir-Abdollahian told reporters in New York, referring to Britain, France, Russia, China and Germany.

"We see a constructive type of negotiation that will lead to tangible verifiable results in the foreign policy of the new government in Iran," the foreign minister added during a press conference on the sidelines of the UN General Assembly.

Asked what Amir-Abdollahian meant by "very soon," a senior Iranian official said on condition of anonymity that "it can mean a few days, it can mean a few weeks."

"As soon as we finish the review process, without any time to be wasted, we shall return to the negotiations table," the official said.

European nations are trying to kick start the deal, known as the Joint Comprehensive Plan of Action, that Trump pulled America out of in 2018. He reinstated sanctions on Iran that Washington had lifted as part of the agreement.

Since then, Tehran has also retreated from many of its commitments.

Trump's successor Joe Biden has indicated he wants to return to the deal, but his administration has expressed impatience at the stalled talks.

"From the White House, we keep receiving diplomatic contradictory messages," said Amir-Abdollahian.

"In the last few months, we have not seen an iota of positive action by the United States administration."