Iran has agreed to hold a fourth round of nuclear talks with the United States on Sunday in Oman, Foreign Minister Abbas Araqchi said on Friday, adding that the negotiations were advancing.

US President Donald Trump, who withdrew Washington from a 2015 deal between Tehran and world powers meant to curb its nuclear activity, has threatened to bomb Iran if no new deal is reached to resolve the long-standing dispute.

Trump’s special envoy, Steve Witkoff, plans to attend the talks in Oman, a source familiar with the matter said on Friday.

Western countries say Iran’s nuclear programme, which Tehran accelerated after the US walkout from the now moribund 2015 accord, is geared toward producing weapons, whereas Iran insists it is purely for civilian purposes.

“The negotiations are moving forward, and naturally, the further we go, the more consultations and reviews are needed,” Araqchi said in remarks carried by Iranian state media.

“The delegations require more time to examine the issues that are raised. But what is important is that we are on a forward-moving path and gradually entering into the details.”

Witkoff, in an interview with Breitbart News, said the Iranians had stated that they do not want a nuclear weapon and the United States will “take them at their word” on this point.

“If that’s how they feel, then their enrichment facilities have to be dismantled. They cannot have centrifuges. They have to downblend all of their fuel that they have there and send it to a faraway place — and they have to convert to a civil programme if they want to run a civil programme,” he said.

The fourth round of indirect negotiations, initially scheduled for May 3 in Rome, was postponed, with mediator Oman citing “logistical reasons”.

In a separate statement on Friday, Omani Foreign Minister Sayyid Badr Albusaidi said that after “coordination with both Iran and the US”, the fourth round of negotiations was set to take place on Sunday in Muscat.

Araqchi said his planned visit to Qatar and Saudi Arabia on Saturday was in line with “continuous consultations” with neighbouring countries to “address their concerns and mutual interests” about the nuclear issue.