Despite both Washington and Tehran taking a tough stance in public ahead of the talks on Iran's uranium enrichment, Iranian Foreign Minister Abbas Araqchi said there was potential for progress after Oman made several proposals during the talks.
"We have just completed one of the most professional rounds of talks ... We firmly stated Iran's position ... The fact that we are now on a reasonable path, in my view, is itself a sign of progress," Araqchi told state TV.
"The proposals and solutions will be reviewed in respective capitals ... and the next round of talks will be scheduled accordingly."
A senior US official said the talks lasted more than two hours and were both direct and indirect with Omani mediators.
"The talks continue to be constructive - we made further progress, but there is still work to be done. Both sides agreed to meet again in the near future. We are grateful to our Omani partners for their continued facilitation," the official said.
The stakes are high for both sides. President Donald Trump wants to curtail Tehran's potential to produce a nuclear weapon that could trigger a regional nuclear arms race and perhaps threaten Israel. The Islamic Republic, for its part, wants to be rid of devastating sanctions on its oil-based economy.
Omani Foreign Minister Badr Albusaidi said on X the talks between Araqchi and Trump's Middle East envoy Steve Witkoff had ended "with some but not conclusive progress".
Ahead of the talks, Araqchi wrote on X: "Zero nuclear weapons = we Do have a deal. Zero enrichment = we do NOT have a deal. Time to decide."
Among remaining stumbling blocks are Tehran's refusal to ship abroad its entire stockpile of highly enriched uranium - possible raw material for nuclear bombs - or engage in discussions over its ballistic missile programme.
Diplomats have said reaching a concrete deal before the summer would technically be impossible given the complexities of an accord. In the meantime, a senior Iranian official involved in nuclear talks with the US said "if Washington drops its 'zero enrichment' demand, a political agreement is feasible."
US Secretary of State Marco Rubio said on Tuesday that Washington was working to reach an accord that would allow Iran to have a civil nuclear energy program but not enrich uranium, while acknowledging that this "will not be easy".
Iranian Supreme Leader Ayatollah Ali Khamenei, who has the last say on matters of state, rejected demands to stop refining uranium as "excessive and outrageous", warning that such talks were unlikely to yield results.
Iran says it is ready to accept some limits on enrichment, but needs watertight guarantees that Washington would not renege on a future nuclear accord.
