NUCLEAR talks between Iran and the United States will take place tomorrow in Oman.

The announcement by Iranian Foreign Minister Abbas Araghchi came after hours of indications that the anticipated discussions were faltering over changes in the format and content of the talks.

US President Donald Trump, meanwhile, sent a blunt warning to Iran’s Supreme Leader Ayatollah Ali Khamenei ahead of the talks.

He told NBC News that the ayatollah “should be very worried.”

Turkey had been working behind the scenes to host talks in Istanbul with regional countries taking part and discussions focused on issues like Iran’s ballistic missile programme and other concerns.

On Wednesday, a regional official said Iran was seeking a “different” type of meeting focused exclusively on the issue of Iran’s nuclear programme, with participation limited to Iran and the US. Mr Trump tore up the previous agreement on Iran’s nuclear programme in 2018.

A White House official said several Arab and Muslim leaders urged the Trump administration on Wednesday not to walk away from talks.

The source added that the White House remains “very sceptical” that the talks will be successful but has agreed to go along out of respect for allies in the region. Mr Araghchi has previously referred to multiple countries working to preserve peace in the Middle East, pointedly adding: “None of them are in Europe.”

US Secretary of State Marco Rubio said the US hoped to discuss a number of concerns beyond the nuclear issue, including discussions on Iran’s ballistic missiles, support for armed groups (such as the Houthis or Hezbollah) across the region and the “treatment of their own people.”

“The leadership of Iran at the clerical level does not reflect the people of Iran. I know of no other country where there’s a bigger difference between the people who lead the country and the people who live there,” he told reporters.