Talks to revive the Iran nuclear deal will be held in Vienna on Friday before breaking for a "few days", Iran's chief negotiator Ali Bagheri Kani said.
The indirect US-Iran talks on bringing both sides back into full compliance with the deal are in their seventh round.
Bagheri Kani said on Twitter that he met EU political director Enrique Mora and other delegates on Thursday "to take stock of the situation and discuss the way forward".
"We have made good progress this week. We will convene a Joint Commission today and will continue talks after a break of a few days," he said.
He did not give a date.
Three diplomats said on Thursday the remaining parties to the 2015 Iran nuclear deal planned to meet on Friday at 1300 GMT to adjourn talks on salvaging the deal. One of them said the talks would resume on 27 December, while another said they would resume between Christmas and the New Year.
Under the agreement, Iran had limited its nuclear programme in return for relief from US, European Union and UN sanctions.
Then-President Donald Trump pulled the United States out of the accord in 2018 and reimposed US sanctions, prompting Iran to begin violating its nuclear restrictions in 2019.