Iran is "more determined than ever" to reach a fair agreement with the US on its nuclear programme, Foreign Minister Abbas Araghchi said on Thursday after mediator Oman announced the fourth round of talks with America had been postponed.
"Together with Omani and US interlocutors, we have decided to postpone the fourth round of talks for logistical and technical reasons," Mr Araghchi said about the talks that were set to take place in Rome on Saturday.
"In fact, we are more determined than ever to achieve a just and balanced deal."
Oman's Foreign Minister Badr Al Busaidi, who has mediated the three rounds of indirect talks that have taken place so far between Washington and Tehran, earlier on Thursday said the negotiations had been postponed for "logistical reasons."
New dates will be announced when agreed on, he added.
In an interview with Fox News on Thursday, US Secretary of State Marco Rubio said Iran should not be afraid of nuclear inspections.
"Iran likes to say they’re not interested in nuclear weapons. They like to say all they want is peaceful nuclear energy," he said. "Then they should not be afraid of inspections by inspectors of any kind, including Americans."
Mr Rubio added that the Iranians can enable real economic development in their country, but they must cease sponsoring militant groups and Yemen's Houthi rebels, stop "building long-range missiles that have no purpose to exist other than having nuclear weapons, and they have to walk away from enrichment".
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 the third, which featured the start of technical discussions, also in Muscat.
The US "never confirmed to be participating in a fourth round of talks with Iran, which people had believed were Saturday in Rome," State Department spokeswoman Tammy Bruce told reporters.
"But we expect another round of talks will take place in the near future," she added.
Washington on Wednesday imposed sanctions on entities it accused of being involved in the illicit trade of Iranian petroleum and petrochemicals. The action is the latest move against Tehran since US President Donald Trump restored his "maximum pressure" campaign on Iran after beginning his second term in January.
Mr Trump on Thursday vowed to punish countries that buy oil from Iran, implicitly threatening new sanctions on China. He said any countries that continue to buy Iranian oil would be prohibited from doing business with the US “in any way, shape or form”.
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.