The Vienna-based International Atomic Energy Agency (IAEA) said earlier this month it was in discussions with Tehran after Bloomberg News reported that the watchdog's inspectors in Iran had found uranium enriched to 84 percent purity.

Iran denied the report, insisting it had not made any attempt to enrich uranium beyond 60 percent, well beyond the 3.67 percent threshold set out in a landmark agreement reached with world powers in 2015.

On Monday, the Atomic Energy Organization of Iran said Grossi would travel to Iran "in the coming days" following an official invitation from its director, Mohamamd Eslami.

"In recent days, we have had constructive and promising discussions" with the IAEA delegation that was already in Iran to clear up any doubts about its nuclear programme, AEOI spokesman Behrouz Kamalvandi said.

"It is hoped that this trip will form the basis for greater cooperation and a clearer horizon between Iran and the IAEA," he added.

The latest visit by the IAEA inspectors comes amid deadlock in negotiations on reviving the 2015 deal that promised Iran relief from crippling economic sanctions in exchange for curbs on its nuclear activities.

The restrictions were intended to prevent Iran developing a nuclear weapons capability, an ambition it has always denied.

The United States unilaterally withdrew from the deal in 2018 and reimposed sanctions, prompting Iran to suspend the implementation of its own commitments under the accord known formally as the Joint Comprehensive Plan of Action, or JCPOA.