UN nuclear watchdog chief Rafael Grossi has pressed Iran to report on missing highly enriched uranium and allow inspections at nuclear sites bombed in June.

Speaking at the World Economic Forum in Davos, he warned that the standoff cannot continue indefinitely.

The International Atomic Energy Agency (IAEA) has inspected all 13 declared Iranian nuclear facilities that were not damaged in recent attacks. However, it has been unable to verify three key sites—Natanz, Fordow, and Isfahan—that were bombed by the United States and Israel last June.

Grossi stressed that Iran must submit a special report detailing what happened to the affected sites and the estimated 440.9 kg of uranium enriched to up to 60% purity. This amount is dangerously close to weapons-grade levels and could theoretically produce around 10 nuclear bombs if further enriched, according to IAEA standards.

Urgent call for Iran’s compliance

“This cannot go on forever because at some point, I will have to say, ‘Well, I don’t have any idea where this material is,’” Grossi told Reuters. He added that while the agency has no current reason to suspect diversion, Iran must engage to maintain transparency.

The IAEA chief underscored that compliance with the Nuclear Non-Proliferation Treaty (NPT) is mandatory and cannot be selective. “Parties to the NPT do not have an ‘a la carte’ option where they can pick and choose what to comply with,” he said.

It has been at least seven months since the IAEA last verified Iran’s stock of highly enriched uranium, despite guidance recommending monthly checks.

Inspections delayed by civil unrest

Grossi acknowledged that recent protests in Iran made it unfeasible to inspect facilities. Iranian officials have indicated that the unrest has subsided, raising the possibility of resuming inspections soon.

He also referenced ongoing diplomatic efforts, including US envoy Steve Witkoff’s negotiations, aimed at reaching a broader agreement between Iran and the United States. “I cannot ignore it, and I wish it well so that there can be an understanding without the looming threat of new military activity,” he said.

The latest IAEA inspections of Iran’s operational nuclear sites occurred in late December, while bombed sites remain unverified. Grossi plans to meet Iranian Foreign Minister Abbas Araqchi in the coming days or weeks.