Iranian lead negotiator, Foreign Minister Araghchi and Trump's Middle East envoy Steve Witkoff held a third round of the talks in Muscat through Omani mediators for around six hours on Saturday, a week after a second round in Rome that both sides described as constructive. The two nations' experts also held a technical meeting on the sidelines of the meeting.
A senior US administration official described the talks as positive and productive, adding that both sides agreed to meet again in Europe "soon", Reuters reported on Saturday.
"There is still much to do, but further progress was made on getting to a deal," the official added.
Earlier Omani Foreign Minister Badr Albusaidi had said talks would continue next week, with another "high-level meeting" provisionally scheduled for May 3. Araqchi said Oman would announce the venue.
Ahead of the lead negotiators' meeting, expert-level indirect talks took place in Muscat to design a framework for a potential nuclear deal.
"The presence of experts was beneficial ... we will return to our capitals for further reviews to see how disagreements can be reduced," Araghchi said in an interview with national Iranian TV after the talks.
An Iranian official, briefed about the talks, told Reuters earlier that the expert-level negotiations were "difficult, complicated and serious".
The only aim of these talks, Araghchi said, was "to build confidence about the peaceful nature of Iran's nuclear programme in exchange for sanctions relief".
ISNA