The UN nuclear watchdog is “increasingly concerned” about a uranium-enrichment plant at Isfahan that Iran declared to it last year but has still not let the watchdog inspect, it said in a confidential report on Iran on Friday seen by Reuters.

Axar.az informs, citing the outlet, Iran has not let International Atomic Energy Agency inspectors return to any of its nuclear facilities bombed by Israel and the United States in a 12-day campaign in June last year that destroyed or badly damaged Iran’s other uranium enrichment plants, the heart of its nuclear program.

The targets included a tunnel network at Isfahan where diplomats have said they believe the Isfahan Fuel Enrichment Plant (IFEP) — declared to the agency on June 12, 2025 — is located, though a senior diplomat said that its whereabouts and status remained unknown.

The IAEA had planned to inspect the plant on June 13, 2025 but the bombing campaign started that day, making it impossible.

“The Agency does not know IFEP’s exact location, status for safeguards purposes or whether it contains nuclear material,” the confidential IAEA report to member states said, adding that “the Agency is also increasingly concerned that Iran has not permitted the Agency” to inspect the plant or see design plans.

While the report singled out IFEP, it also reiterated that Iran should inform the IAEA of the status of its enrichment plants as well as its stock of highly enriched uranium, which includes material close to weapons grade, and let inspectors return to the bombed sites and account for the enriched uranium.

“The Agency’s lack of information about this nuclear material and access to facilities to verify it is a matter of serious proliferation concern .... and needs to be rectified with the utmost urgency,” it said.