The United States and Iran have made significant progress in talks aimed at resolving a longstanding nuclear dispute and averting new US strikes, mediator Oman said.
It comes amid Washington's large-scale military build up in the Middle East.
The two sides plan to resume negotiations soon after consultations in their countries' capitals, with technical-level discussions scheduled to take place next week in Vienna, Omani Foreign Minister Sayyid Badr Albusaidi said in a post on X after the day's talks ended in Switzerland.
Any substantial move toward an elusive agreement between longtime foes Washington and Tehran could reduce the imminent prospects for US President Donald Trump to carry out a threatened attack on Iran that many fear could escalate into a wider war.
The Omani minister's upbeat assessment followed indirect talks between Iranian Foreign Minister Abbas Araqchi and US envoys Steve Witkoff and Jared Kushner in Geneva, with one session in the morning and the second in the afternoon.
"We have finished the day after significant progress in the negotiation between the United States and Iran," Badr Albusaidi said.
Describing the talks as some of the most serious that Iran has had with the US, Mr Araqchi told Iranian state television: "We reached agreement on some issues, and there are differences regarding some other issues."
"It was decided that the next round of negotiations will take place soon, in less than a week," he said, adding the Iranians had clearly expressed their demand for sanctions relief.
There was no immediate comment from US negotiating team on the outcome of the talks.
The discussions about the decades-long dispute over Iran's nuclear work come as fears grow of a Middle East conflagration.
Mr Trump has repeatedly threatened action if there is no deal and the US military has amassed its forces in waters near the Islamic Republic.
'Intense and serious' talks
A senior Iranian official earlier told Reuters that the US and Iran could reach a framework for a deal if Washington separated "nuclear and non-nuclear issues".
The Trump administration has insisted that Iran's missile programme and other issues must be part of the negotiations.
After the morning session, Mr Badr Albusaidi said the two sides had exchanged "creative and positive ideas".
But a senior Iranian official said at the time that some gaps still had to be narrowed.
Washington, which believes Tehran seeks the ability to build a nuclear bomb, wants Iran to give up all uranium enrichment, a process that makes fuel for atomic power plants but that can also yield material for a warhead.
Iran has long denied wanting a bomb and said earlier it would show flexibility at the talks.
Reuters reported on Sunday that Tehran was offering undefined new concessions in return for removal of sanctions and recognition of its right to enrich uranium.
However, the US also wants to expand talks to other issues including Iran's arsenal of ballistic missiles and its support for armed groups in the region.
US Secretary of State Marco Rubio said yesterday that Iran's refusal to discuss its ballistic missile programme was a "big problem" that would have to be addressed eventually, as the missiles were "designed solely to strike America" and pose a threat to regional stability.
"If you can't even make progress on the nuclear programme, it's going to be hard to make progress on the ballistic missiles as well," Mr Rubio told reporters in Saint Kitts.
Iranian foreign ministry spokesperson Esmaeil Baghaei told Press TV that the negotiations would focus solely on nuclear topics and the lifting of sanctions, and said Tehran goes into them with "seriousness and flexibility".
Trump threatens 'really bad things'
Mr Trump said on 19 February that Iran must make a deal in ten to 15 days, warning that "really bad things" would otherwise happen.
He briefly laid out his case for a possible attack on Iran in his State of the Union speech, underlining that while he preferred a diplomatic solution, he would not allow Tehran to obtain a nuclear weapon.
In June last year, the US joined Israel in hitting Iranian nuclear sites and has been ramping up the pressure on Tehran again since January, when Mr Trump threatened to intervene over its crushing of nationwide protests with thousands killed.
Since then, Mr Trump has deployed fighter jets and aircraft carrier strike groups in the region, hoping to pressure Iran into concessions.
Iran responded to last summer's strikes by firing fusillades of missiles at Israel and has threatened to retaliate fiercely if attacked again, raising fears of a wider regional conflict that has alarmed Gulf oil producers.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
Several countries have begun withdrawing dependents of diplomatic personnel and non-essential staff from some locations in the Middle East, or advising citizens to avoid travel to Iran.
The USS Gerald R. Ford, the biggest US aircraft carrier, left port near the Greek island of Crete on Thursday bound for shores near Haifa in northern Israel, where it is expected to arrive on Friday.
The US has also sent around a dozen F-22 fighter jets to Israel - the first time Washington has deployed combat aircraft to the country for potential wartime operations, a US official said.
The Trump administration has not formally announced the deployment. The Pentagon declined to comment.
But the sides remain sharply divided - even over the scope and sequencing of relief from US sanctions - a senior Iranian official told Reuters.
Within Iran, Supreme Leader Ayatollah Ali Khamenei faces the gravest crisis of his 36-year tenure, with an economy buckling under tightened sanctions and renewed protests following the major unrest and crackdown in January.
President Masoud Pezeshkian said that Mr Khamenei has banned weapons of mass destruction, which "clearly means Tehran won't develop nuclear weapons," reiterating a fatwa issued in the early 2000s.
