Rafael Grossi
Rafael GrossiReuters

The International Atomic Energy Agency (IAEA) has been urging Iran to remove its ban on several inspectors responsible for monitoring uranium enrichment at Iranian nuclear sites, but the head of the organization on Wednesday expressed doubts about the possibility of this occurring.

"Unfortunately this ship has sailed," Rafael Grossi, head of the IAEA, told Reuters during an interview which was held at the UN General Assembly.

The IAEA has strongly criticized Iran’s decision from a year ago, calling it "unprecedented" and describing it as a "very serious blow" to the agency’s ability to conduct effective inspections of Iran’s nuclear sites.

In June, the IAEA’s 35-member Board of Governors passed a resolution urging Iran to enhance cooperation with the agency and reverse the exclusion of those inspectors, a process known as "de-designation."

"Until a few months ago they said they were considering it, and now they say they are not going to reincorporate these inspectors to the list, so unfortunately this ship has sailed," Grossi told Reuters.

Iran has gradually scaled back its compliance with the 2015 nuclear deal it signed with world powers, in response to then-US President Donald Trump’s withdrawal from the deal in 2018.

One of those moves included a ban of several IAEA inspectors from the country. Those inspectors were responsible for verifying Iran's compliance with the 2015 deal.

The IAEA has long sought answers from Iran regarding the origin and current location of man-made uranium particles found at two undeclared sites, Varamin and Turquzabad, as part of the IAEA's years-long investigation.

In addition, the IAEA has published several reports which have found that Iran has significantly expanded its stockpile of uranium enriched to levels close to weapons-grade, defying international demands.

Grossi said on Tuesday he had sensed a greater willingness by Iranian officials to engage with the agency in a more meaningful way and added that he is aiming to meet with Iran’s newly elected President Masoud Pezeshkian next month.

It remains uncertain whether Grossi will push for the reinstatement of the inspectors who have specialized knowledge of Iran’s uranium enrichment operations.