"The technical consultative meeting between the two countries, which was to be held as part of the indirect talks between the two sides on Wednesday, has been postponed to Saturday," foreign ministry spokesman Esmaeil Baqaei said.

He said the decision to reschedule the meeting was made "following Oman's proposal and the agreement of the Iranian and American delegations".

The reason for the delay was not immediately clear.

Tehran and Washington have held two rounds of indirect talks in Muscat and Rome since April 12, with Iranian Foreign Minister Abbas Araghchi and US Middle East envoy Steve Witkoff leading the negotiations.

Oman said the third round, also set for Saturday, would again be held in Muscat.

The talks earlier this month in the Omani capital were the first discussions at such a high level between the foes since US President Donald Trump abandoned a landmark nuclear accord in 2018.

Following Saturday's latest round in Rome, Araghchi said the meeting was "good" and that the negotiations were "moving forward".

On Monday, Trump said Washington had "very good meetings" on Iran.

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.

Later on Tuesday, Baqaei said Araghchi was heading to China for talks.

Iran has in recent weeks engaged with its allies China and Russia over its nuclear programme.

Before leaving for Beijing, Araghchi spoke with UN nuclear chief Rafael Grossi and briefed him on the latest developments in talks with the United States, a foreign ministry statement said.