Rafael Mariano Grossi, Director General of the International Atomic Energy Agency. (Photo: AFP/VNA)

Khatibzadeh said that Iran is waiting for Grossi to respond to its invitation. In his next trip, Grossi will meet the head of the Atomic Energy Organization of Iran (AEOI) as well as Iran's foreign minister, said Khatibzadeh.

The invitation comes days after the UN's nuclear watchdog chief called the lack of communication from Tehran "astonishing."

Mr. Grossi last visited Tehran in September, when he reached an agreement on access to monitoring equipment at Iran's nuclear facilities.

In early September, the IAEA released a report stating that its nuclear inspection mission in Iran had been seriously impaired after Tehran suspended some IAEA inspections of nuclear activities.