A pause in negotiations to salvage Iran's nuclear deal with world powers has placed the International Atomic Energy Agency in an "uncomfortable position," IAEA director general Rafael Grossi said on Monday.
An Iranian official announced Saturday the talks in Vienna will not resume before a new government takes office in August, following presidential elections last month won by ultra-conservative Ebrahim Raisi.
"We still have a number of questions, issues that we are trying to clarify with Iran, and we will have to wait and start anew with the new team when they are in office," Grossi told AFP in an interview in Rio de Janeiro during an official visit to Brazil.
The announcement that the process would be resumed only after Raisi takes over "leaves us in a rather uncomfortable situation," added the Argentine official. "I'm talking about the agency, I don't know about the others, but I suppose they would rather be negotiating than waiting."
The Islamic republic has been engaged in indirect negotiations with the United States since April in Vienna on reviving its troubled 2015 nuclear agreement.
The accord formally known as the Joint Comprehensive Plan of Action offered Tehran international sanctions relief in exchange for limiting its nuclear programme, but was torpedoed in 2018 when former US president Donald Trump withdrew from it and reimposed sanctions.
Trump's successor Joe Biden has signalled his readiness to return to the deal but his administration has also voiced growing frustration as the talks drag on.
"We remain open to continuing and ultimately to completing the JCPOA discussions in a productive manner," US State Department spokesman Ned Price told reporters in Washington.
"We recognise, along with the international community, the advantage of a mechanism that ensures permanently and verifiably that Iran cannot acquire a nuclear weapon," he said. "We've also been clear that this offer won't be on the table indefinitely."
Iran has pushed hard for relief of all sanctions but the Biden administration says it is only open to relief on measures taken over its nuclear programme, not on other issues including human rights and support for regional militants.
A sixth round of talks concluded on June 20. They are being brokered by the European Union, which like Britain, China France, Germany and Russia remains in the deal.
Incumbent President Hassan Rouhani had repeatedly promised he would get the United States to lift sanctions before the end of his term, but last week indicated this would no longer be possible and negotiations would not be complete before he leaves office. Raisi will take over from Rouhani on August 5.
Ultimate political power in Iran rests with the supreme leader, Ayatollah Ali Khamenei, who gave the green light for both the original nuclear agreement and the efforts to revive it.