"I will go to Austria to take part in the annual general conference of the International Atomic Energy Agency in Vienna, where I will meet with Director General Rafael Grossi," Iran's chief nuclear negotiator Mohammad Eslami told state television.

The Vienna-based IAEA's annual conference takes place this year from September 26-30.

The UN watchdog said early this month it was "not in a position to provide assurance that Iran's nuclear programme is exclusively peaceful".

It has been pressing for answers on the presence of nuclear material at three undeclared sites and the issue led to a resolution that criticised Iran being passed at a June meeting of the IAEA's board of governors.

The three sites represent a key sticking point in negotiations to restore a tattered 2015 nuclear deal between Iran and world powers.

Those negotiations began in Vienna in April 2021 but have repeatedly stalled.

The US walked out of the original deal under then president Donald Trump in 2018 and re-imposed biting sanctions, provoking Tehran into incrementally stepping back from its nuclear commitments.

Iran has repeatedly said it wants the IAEA to drop its interest in the three sites -- a position that the nuclear watchdog says lacks credibility.

"I hope that my talks will put an end... to the false accusations about certain (nuclear) sites stemming from political pressure and psychological operations exerted against Iran," Eslami added.

In a speech at the UN General Assembly on Wednesday, Iran's President Ebrahim Raisi re-iterated his country's long held insistence that it is not seeking a nuclear weapon.