A fourth round of talks between Iran and the US over Tehran's rapidly advancing nuclear programme planned for Saturday has been postponed, mediator Oman said on Thursday.
"For logistical reasons we are rescheduling the US-Iran meeting provisionally planned for Saturday May 3," Oman's Foreign Minister Badr Al Busaidi said on X.
New dates will be announced when agreed on, he added.
The indirect talks have been held every Saturday for the past three weeks, with Oman hosting the first round in the capital Muscat, the second at its embassy in Rome and third, which featured the start of technical discussions, in Muscat again.
A US source familiar with the negotiations said the American side had "never confirmed its participation" in the fourth round of talks and that the timing and venue were still to be confirmed. "We expect they will take place in the near future.
Iran said on Wednesday the next round of negotiations would be held in Rome on Saturday.
The talks seek to limit Iran’s nuclear programme in exchange for the lifting of crushing economic sanctions the US has imposed on Tehran.
US President Donald Trump has repeatedly threatened to unleash air strikes against Iran’s nuclear infrastructure unless a deal is reached. Iranian officials increasingly warn they could pursue a nuclear weapon with their stockpile of uranium enriched to near weapons-grade levels.
The US on Wednesday imposed sanctions on entities it accused of being involved in the illicit trade of Iranian petroleum and petrochemicals.
The US State Department said it was imposing sanctions on seven entities based in the UAE, Turkey and Iran that it accused of trading Iranian petroleum and petrochemical products. Two vessels were also targeted with sanctions.
US Secretary of State Marco Rubio said in a separate statement that the action targeted four sellers and one buyer of Iranian petrochemicals worth hundreds of millions of dollars.
Wednesday's action is the latest move targeting Tehran since Mr Trump restored his "maximum pressure" campaign on Iran after beginning his second term in January.
"The President is committed to driving Iran’s illicit oil and petrochemical exports – including exports to China – to zero under his maximum pressure campaign," Mr Rubio said.
In his first term from 2017 to 2021, Mr Trump withdrew the US from a 2015 deal between Iran and world powers that had placed strict limits on Tehran's uranium enrichment in exchange for sanctions relief. He also reimposed sweeping US sanctions.
Since then, Iran has far surpassed that deal's limits on uranium enrichment.
Western powers accuse Iran of having a clandestine agenda to develop nuclear-weapon capability by enriching uranium to a high level of fissile purity, above what they say is justifiable for a civilian atomic energy programme. Tehran says its nuclear programme is wholly for civilian power purposes.