Iranian Foreign Minister Abbas Araghchi met the UN nuclear watchdog's director general Rafael Grossi on Monday, accompanied by nuclear experts, before US-Iran nuclear talks resume on Tuesday.
Mr Araghchi said they held "deep technical discussions” in preparation for "important negotiations scheduled for tomorrow in Geneva". Mr Grossi described the meeting in similar terms.
The IAEA has called on Iran to explain what happened to its stockpile of 440kg of highly enriched uranium after three nuclear sites were bombed by Israel and the US last June.
It is also calling on IAEA inspections of nuclear sites to fully resume, including at the Natanz, Fordow and Isfahan sites that were attacked. Mr Grossi says the agency cannot confirm whether Iran's nuclear activities are purely peaceful without further information.
Mr Araghchi was defiant about the US warships sent to the Middle East before the talks with the US, which are intended seek to resolve the dispute over Tehran’s nuclear programme and avert conflict. After Iran agreed to new talks, a first meeting took place in Oman in early February.
“I am in Geneva with real ideas to achieve a fair and equitable deal. What is not on the table: submission before threats,” Mr Araghchi said on X.
Speaking during a visit to Hungary on Monday, US Secretary of State Marco Rubio said reaching a deal with Tehran would be hard.
"I think that there's an opportunity here to diplomatically reach an agreement that addresses the things we're concerned about. We'll be very open and welcoming to that," Mr Rubio said.
"But I don't want to overstate it either. It's going to be hard. It's been very difficult for anyone to do real deals with Iran, because we're dealing with radical Shiite clerics who are making theological decisions, not geopolitical ones."
The US wants to expand the scope of the talks to non-nuclear issues like Iran's missile stockpile, but Tehran says it is only willing to discuss curbs on its nuclear programme in exchange for sanctions relief and refuses zero uranium enrichment.
A previous deal between the US, Iran and other European and world powers collapsed in 2018. A European Commission spokesman, Anouar El Anouni, said the EU welcomed the prospect of further talks.
"We in the European Union remain convinced that diplomacy must be given a chance, but also that a lasting solution to this issue can only be found through diplomatic channels," he said.
"A military escalation could have very serious repercussions for regional stability. Second, it is high time for Iran to demonstrate its seriousness in addressing the concerns of the international community, particularly regarding the nuclear issue."
Israeli Prime Minister Benjamin Netanyahu said on Sunday he told US President Donald Trump last week that any US deal with Iran must include the dismantling of Iran's nuclear infrastructure, not just halting the enrichment process.
Deputy Foreign Minister Majid Takht-Ravanchi signalled Iran's readiness to compromise on its nuclear programme in return for sanctions relief, telling the BBC on Sunday that the ball was “in America's court to prove that they want to do a deal”.
The US has sent a second aircraft carrier to the Middle East and is preparing for the possibility of a sustained military campaign if the talks do not succeed, US officials have told Reuters news agency.
The naval forces of Iran's Islamic Revolutionary Guard Corps were on Monday beginning drills off the country's southern coast. The live-fire drills are being directly supervised by the IRGC's commander-in-chief Mohammad Pakpour, state media said.
It said the drills aim to test the readiness of the IRGC Navy’s operational units and review support programmes and scenarios in the face of "possible security and military threats" in the strategic Strait of Hormuz.
Iran's civil defence organisation on Monday held a chemical defence drill in the Pars Special Economic Energy Zone to strengthen preparedness for potential chemical incidents in the energy hub located in southern Iran.
