Tensions between Iran and the International Atomic Energy Agency (IAEA) have repeatedly flared since a 2015 deal curbing Tehran's nuclear programme in exchange for sanction relief fell apart.

In recent years, Tehran has decreased its cooperation with the IAEA by deactivating surveillance devices needed to monitor the nuclear programme, and barred UN inspectors.

In the report, Grossi said he hoped "an early visit" to Iran would help the "establishment of a fluid, constructive dialogue that swiftly leads to concrete results".

Following his election in July, Pezeshkian indicated that he would meet with Grossi "at the appropriate juncture", the report said.

Grossi last visited Iran in May, in a bid to improve cooperation with Tehran, which was at a level he described at the time as "completely unsatisfactory".

At the same time, Iran has significantly ramped up its nuclear programme and now has enough material to build several atomic bombs.

In a separate confidential report seen by AFP ahead of an IAEA board of governors' meeting next week, the agency said Iran has further increased its stockpiles of highly enriched uranium in recent months.

The report said that Iran has an estimated amount of 164.7 kilogrammes enriched to up to 60 percent -- just a short step from bomb-grade material.

The amount is up by 22.6 kilogrammes since the last report in May.

Iran has always denied any ambition to develop nuclear weapons, insisting its activities are entirely for peaceful purposes.

The landmark 2015 deal 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 -- bringing the US back on board and Iran back into compliance -- have so far been fruitless.