"Iran's stance is not only unprecedented, but unambiguously contrary to the cooperation that is required," the International Atomic Energy Agency (IAEA) said in a confidential report seen by AFP.

Iran in September withdrew the accreditation of several inspectors, a move Teheran described as retaliation for "political abuses" by the United States, France, Germany and Britain.

The IAEA has condemned the move -- which targets eight top inspectors, with French and German nationals among them, according to a diplomatic source.

In the report, the IAEA said it received a letter from Iran on Wednesday, reiterating its position "that it was within its rights" to withdraw the accreditation, but was "exploring possibilities to address the request" of the agency to re-instate it.

IAEA head Rafael Grossi expressed "his hope that this matter will be resolved promptly".

In a separate confidential report seen by AFP, the IAEA said that Iran's estimated stockpile of enriched uranium had reached more than 22 times the limit set out in the 2015 accord between Tehran and world powers.

Iran's total enriched uranium stockpile was estimated at 4,486.8 kilograms (9,891.7 pounds) as of October 28, up by 693.1 kilograms from August, the report said. The limit in the 2015 deal was set at 202.8 kilograms.

In 2015, major world powers reached a deal with Iran, aimed at curbing Tehran's nuclear programme in exchange for the lifting of international sanctions.

That started to unravel in 2018 when then US president Donald Trump unilaterally withdrew from it and reimposed sanctions, and Iran retaliated by stepping up its nuclear activities.

EU-mediated efforts to revive the deal have so far been fruitless.