Tehran - The U.N. nuclear watchdog's chief arrived Friday in Tehran amid hopes of reviving a 2015 accord between Iran and world powers, with Britain saying a deal was 'close.'
The visit by International Atomic Energy Agency head Rafael Grossi, who was set to meet Iranian officials Saturday, is seen as critical to clinching agreement over a return to the nuclear deal and comes in parallel to negotiations in the Austrian capital to salvage the accord.
Grossi 'was received on arrival in Tehran by Behrouz Kamalvandi, spokesman for the Atomic Energy Organization of Iran," the Iranian body said in a statement on its website. He is to meet with its chief Saturday.
'This is a critical time but a positive outcome for everyone is possible,' Grossi wrote on Twitter earlier Friday.
The next few days are widely seen as a crunch point for the negotiations on Iran's nuclear program - the latest round of which started in late November in Vienna.
'We are close. E3 negotiators [are] leaving Vienna briefly to update ministers on [the] state of play,' the head of the British delegation, Stephanie Al-Qaq, said Friday, referring to negotiators from Britain, France and Germany.
She added that they were 'ready to return soon.'
Along with counterparts from China, Iran and Russia, they have been taking part in the latest round of talks in the Austrian capital since late November, with the U.S. participating indirectly.
Grossi had vowed earlier this week that the IAEA would 'never abandon' its attempts to get Iran to clarify the past presence of nuclear material at several undeclared sites.
Iran has said the closure of the probe is necessary to clinch a deal on the nuclear accord.
Grossi is expected to hold a news conference on his return to Vienna.
Ready to go to Vienna
The EU has been chairing the nuclear deal talks, and the bloc's foreign policy chief, Josep Borrell, said Friday that he hoped 'to have results this weekend,' while stressing that there was 'still work ongoing.'
The 2015 deal, formally known as the Joint Comprehensive Plan of Action, was aimed at guaranteeing that Iran's nuclear program could not be used to develop a nuclear weapon - something Tehran has always denied wanting to do.
It began unravelling when then-U.S. President Donald Trump withdrew from it in 2018 and reimposed sanctions, prompting Iran to start disregarding the limits on its nuclear activity laid down in the agreement.
Earlier Friday, Iran's Foreign Minister Hossein Amir-Abdollahian said he was prepared to travel to the Austrian capital if a deal was reached.
'I am ready to go to Vienna when the Western sides accept our remaining red lines,' he said in a phone call with Borrell, quoted in a foreign ministry statement.
While Amir-Abdollahian did not define the 'red lines,' Iran has repeatedly demanded the right to verify the removal of sanctions and for guarantees the U.S. will not repeat its withdrawal from the agreement.
On Thursday, U.S. State Department deputy press spokeswoman Jalina Porter said negotiators were 'close to a possible deal,' but that 'a number of difficult issues' remained unresolved.
However, 'if Iran shows seriousness, we can and should reach an understanding of mutual return to full implementation of the JCPOA within days,' she added.