Iran's foreign ministry said on Thursday that the fourth round of nuclear talks with the United States has been postponed, after mediator Oman cited "logistical reasons" for the delay.

Tehran and Washington were scheduled to meet for a fourth round of talks on Saturday in Rome, after the two sides reported progress in previous rounds.

"The next round of indirect Iran-US talks, which were scheduled to be held in Rome on Saturday... has been postponed," Iranian foreign ministry spokesman Esmaeil Baqaei said in a statement.

He added the decision was based on the proposal by Oman and that "the next possible date will be announced later."

Earlier, Oman's top diplomat Badr Albusaidi cited "logistical reasons" for the delay.

"For logistical reasons we are rescheduling the US-Iran meeting provisionally planned for Saturday May 3. New dates will be announced when mutually agreed," he said on X.

On Friday, Iranian diplomats were due to meet with representatives from Germany, Britain, and France in Rome ahead of talks with the US.

It remains unclear whether these talks will be held as scheduled.

The Iran-US talks mediated by Oman, which began on April 12, have been the highest-level contact in years since US President Donald Trump abandoned a nuclear accord with world powers in 2018.

Since returning to office, Trump has revived his "maximum pressure" approach against Tehran.

In March, he wrote to Iran's supreme leader, Ayatollah Ali Khamenei, proposing talks but warning of potential military action if diplomacy failed.

Western countries, including the United States, have long accused Iran of seeking to acquire nuclear weapons – an allegation Tehran has consistently denied, insisting that its programme is for peaceful civilian purposes only. (AFP)