Iran has said it is prepared to discuss curbs on its nuclear programme in return for the lifting of sanctions, but has repeatedly ruled out linking the issue to other questions, including missiles.

Takht-Ravanchi confirmed that a second round of nuclear talks would take place on Tuesday in Geneva, after Tehran and Washington resumed discussions in Oman earlier this month.

“(Initial talks went) more or less in a positive direction, but it is too early to judge,” Takht-Ravanchi told the BBC.

A US delegation, including envoys Steve Witkoff and Jared Kushner, will meet with the Iranians on Tuesday morning, a source had told Reuters on Friday, with Omani representatives mediating the US-Iran contacts.

Iran’s atomic chief said on Monday the country could agree to dilute its most highly enriched uranium in exchange for all financial sanctions being lifted.

Takht-Ravanchi used this example in the BBC interview to highlight Iran’s flexibility.

The senior diplomat reiterated Tehran’s stance that it would not accept zero uranium enrichment, which had been a key impediment to reaching a deal last year, with the US viewing enrichment inside Iran as a pathway to nuclear weapons.

Iran denies seeking such nuclear weapons.

During his first term in office, Trump pulled the US out of a 2015 Iran nuclear agreement, known as the Joint Comprehensive Plan of Action, the signature foreign policy achievement of former Democratic president Barack Obama.

The deal eased sanctions on Iran in exchange for Tehran limiting its nuclear programme to prevent it from being able to make an atomic bomb.