The UN nuclear watchdog on Tuesday said it was seeking "common ground" with Iran days after reporting that Tehran had sharply increased its stockpile of highly enriched uranium.
International Atomic Energy Agency chief Rafael Grossi met officials including Iran's atomic energy chief, Mohammad Eslami, in Tehran before negotiations next week aimed at salvaging the 2015 nuclear deal.
Mr Grossi also met Iranian Foreign Minister Hossein Amirabdollahian, who urged the agency to "avoid taking political positions".
The IAEA said Iran had boosted its stockpile of highly enriched uranium to many times in excess of the limit laid down in the accord.
"Our work has been intense since the morning," Mr Grossi said in Tehran, alongside Mr Eslami, head of the Atomic Energy Organisation of Iran.
"We are continuing at this point the negotiations with a view to find a common ground.
"There are other issues that we are working on and … it is very important to put this into the perspective of the peaceful nuclear programme of Iran.
"We are multiplying our efforts with a view to conclude our exchanges today."
The Atomic Energy Organisation of Iran said: "Establishing a clear framework for co-operation between the IAEA and the agency is one of the main topics of discussion."
It was Mr Amirabdollahian's first meeting with Mr Grossi.
"The agency must co-operate with Tehran within the framework of its technical functions and avoid taking political positions," he said.
Tehran has repeatedly accused the UN nuclear watchdog of favouring a western agenda.
Mr Amirabdollahian emphasised "the importance of the technical and impartial work of the agency, which must ignore foreign political pressure", the Foreign Ministry said.
"Iran and the IAEA have agreed to resolve the outstanding technical problems between the two parties in the coming months," it said.
Negotiations resume on Monday between Tehran and world powers in a bid to revive the 2015 deal that gave Iran sanctions relief in return for limits to its nuclear programme.
On November 12, Mr Grossi described as "astonishing" his lack of contact with the new Iranian government of ultra-conservative President Ebrahim Raisi.
Days later, Tehran responded by announcing it had invited the watchdog chief to visit.
On Monday, Iran's Foreign Ministry spokesman Saeed Khatibzadeh expressed hopes that the visit would be "constructive".
"We have always advised the IAEA to stay on the path of technical co-operation and to not let certain countries pursue their political orientations on behalf of the IAEA," Mr Khatibzadeh said.
Iran began easing its commitments under the deal in 2019, a year after then president Donald Trump withdrew the US from the accord and began reimposing sanctions.
Mr Trump's successor Joe Biden wants to return the agreement. Tehran is demanding that all sanctions imposed or reimposed on it by the US since then be lifted.
The IAEA said last Wednesday that Iran had boosted its stockpile of highly enriched uranium to 2,489.7 kilograms.
The total amount now includes 113.8 kg enriched to 20 per cent, up from 84.3kg in September, and 17.7kg enriched up to 60 per cent, up from 10kg, the agency said.
The US has warned that Iran was reaching the point of no return for reviving the nuclear deal.
"The time will come if Iran continues at this pace with the advancements they've made, it will make it impossible even if we were going to go back to the [nuclear deal] to recapture the benefits," the US envoy for Iran, Robert Malley, said on Friday.
The November 29 talks will be held in Vienna, where the UN agency is based.
The other parties to the deal – Britain, China, France, Germany and Russia – will join the talks while the US will take part indirectly.