Iran in September withdrew the accreditation of several inspectors of the International Atomic Energy Agency (IAEA).

The measure is the latest to raise tensions as a 2015 deal curbing Tehran's nuclear programme in exchange for sanction relief has fallen apart.

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

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

The inspectors are crucial to the IAEA's work in Iran as they have "rare expertise and knowledge of the locations," another diplomatic source said.

Teheran has described its decision as retaliation for "political abuses" by the United States, France, Germany and Britain.

- 'No progress' -

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".

The agency also once again deplored that there had been "no progress in resolving" other outstanding matters.

These include reinstalling cameras to monitor Tehran's nuclear programme and explaining uranium traces at undeclared sites.

As part of its steps since the US withdrew from the deal, Iran deactivated surveillance devices needed by the IAEA to monitor the country's nuclear programme.

In a separate confidential report seen by AFP ahead of next week's IAEA board of governors' meeting, the agency said that Iran's estimated stockpile of enriched uranium had reached more than 22 times the limit set out in the 2015 accord.

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

Tehran has, however, slowed down the pace at which it produces uranium enriched to 60 percent since spring, according to the IAEA report.

Enrichment levels of around 90 percent are required for use in a nuclear weapon.

- Heightened tensions -

Experts see this as a possible sign of Iran wanting to defuse tensions, with one of the diplomatic sources describing it as "likely... a political decision".

In recent months, US President Joe Biden's administration had strived to keep a lid on Middle East troubles through quiet diplomacy with Tehran.

But that bet came crashing down with the October 7 attacks by Hamas against Israel.

Tensions between Iran and the United States have worsened since the attacks and Israel's subsequent relentless bombardment and ground offensive in Gaza.

Washington and Tehran have mutually accused each other of aggravating the situation.

The 2015 deal between major world powers and Iran first started to unravel in 2018 when then US president Donald Trump unilaterally withdrew from it and reimposed sanctions.

Iran retaliated by stepping up its nuclear activities.

EU-mediated efforts to revive the deal -- bringing the US back on board and Iran back into compliance -- have so far been fruitless.

The EU announced formally last month that it would maintain sanctions "under the EU non-proliferation regime on Iran".

The decision to keep the sanctions in place was originally announced by Britain, France, and Germany, all signatories to the pact, in September.

The sanctions remaining in place include blacklisting missile manufacturers and affiliates of Iran's Revolutionary Guards.