US and Iranian officials have made "significant progress" in high-stakes nuclear talks in Geneva, Oman's foreign minister has said, but the chances of a deal that could avert a war remain unclear.

Badr Albusaidi, who was mediating, said the two sides planned to resume negotiations "soon" after consultations in their capitals, and technical-level discussions would take place next week in Vienna.

Iran's Foreign Minister Abbas Araghchi, who led his country's delegation, said "good progress" had been made and while there had been agreement on some issues, differences remained on others.

He said more negotiations would happen in a less than a week. There has been no official reaction from the US.

The prospect of further talks could reduce the possibility of President Donald Trump carrying out his threats to strike Iran.

Trump has ordered the largest US military build-up in the Middle East since the US-led invasion of Iraq in 2003, while Iran has vowed to respond to an attack with force.

For decades, the US and Israel have accused Iran of trying to secretly develop a nuclear weapon. Iran has repeatedly denied it is seeking a bomb and says its programme is only for peaceful purposes, though the country is the only non-nuclear-armed state to have enriched uranium at near weapons-grade level.

According to Iranian state media, negotiators insisted that Iran had the right to peaceful nuclear energy and rejected US demands to completely stop the enrichment of uranium in Iranian territory and to transfer its stockpile of 400kg (880lb) of enriched uranium out of the country.

But officials are believed to have offered concessions, although the proposals have not been made public. One of the reported options was for Iran to be allowed to enrich uranium at a minimal level after a three-to-five-year suspension, under international monitoring.

In return for a deal, Araghchi told Iranian television that the negotiators demanded the lifting of sanctions that have crippled Iran's economy.

Opponents of the regime say any relief would give the clerical rulers a lifeline.

The indirect talks happened in two sessions. One in the morning, that lasted three hours, and another, shorter, in the evening.

As in previous rounds, the US was represented by special envoy Steve Witkoff and Trump's son-in-law, Jared Kushner. Rafael Grossi, the head of the global nuclear watchdog, the International Atomic Energy Agency (IAEA), also joined the negotiations.

It remains unclear which conditions Trump could find acceptable for a deal, and the president has done little to explain why there could be the need to take military action now, eight months after the US bombed Iranian nuclear facilities during a war between Israel and Iran.

Iran has already rejected discussing limits to the country's ballistic missile programme and ending its support for proxies in the region, including Hamas in Gaza, Hezbollah in Lebanon, militias in Iraq, and the Houthis in Yemen.

In recent weeks, the US has sent thousands of troops and what Trump has described as an "armada" to the region, including two aircraft carriers along with other warships, as well as fighter jets and refuelling aircraft.

Trump first threatened to bomb Iran last month as security forces brutally repressed anti-government protests, killing thousands of people. But since then, his focus has turned to Iran's nuclear programme, which has been at the centre of a long-running dispute with the West.

In his State of the Union speech to Congress on Tuesday, Trump briefly and vaguely talked about the tensions with Iran, without clearly laying out the case for strikes.

He said Iran was working to build missiles that would "soon" be capable of reaching the US, without giving details. He also accused the country of trying to "start all over again" with a nuclear weapons programme following last year's strikes, and said he could not allow the "world's number one sponsor of terror... to have a nuclear weapon".

Hours before the speech, however, the Iranian foreign minister posted on social media that Iran would "under no circumstances ever develop a nuclear weapon".

The US struck three nuclear sites in Iran last June, as it joined Israel in its bombing campaign.

At the time, Trump said the facilities had been "obliterated". Iran says its enrichment activity stopped after the attacks, although it has not allowed the IAEA inspectors to access the damaged sites.

Reports in US media, quoting unnamed administration officials, have suggested that Trump was considering an initial strike in the coming days on Iran's Revolutionary Guards or nuclear sites to pressure the country's leaders.

If negotiations failed, according to the reports, the president might go as far as ordering a campaign with the aim of toppling Iranian Supreme Leader, Ayatollah Ali Khamenei.

The Chairman of the Joint Chiefs of Staff is also said to have warned that strikes against Iran could be risky, potentially drawing the US into a prolonged conflict, although Trump has insisted that Gen Dan Caine believes it would be "easily won".

Iran, meanwhile, has threatened to respond to any attack by striking American military assets in the Middle East and Israel.

US-allied countries in the region are concerned that an attack on Iran could lead to a wider conflict, and have warned air power alone will not be able to change the country's leadership.

Israeli Prime Minister Benjamin Netanyahu, however, has warned against a deal that does not include Iran's ballistic missiles and its proxies.

Netanyahu has long described Iran as a key threat for Israel, and a source of instability in the region.

Analysts believe that the prime minister, who visited the White House earlier this month, may be pushing for a campaign with the goal of toppling the Iranian regime.

The US has the world's second-largest nuclear arsenal. Israel is also believed to have nuclear weapons, although it neither confirms nor denies this.