Officials from the International Atomic Energy Agency (IAEA) have been on the ground monitoring the plant since September 2022, six months after it was captured by Moscow's forces.

Responding to an IAEA statement saying their team had been blocked from reactor halls, Renat Karchaa, an official at Russia's Rosatom, alleged they tried to access "containment shells".

"A containment shell, and especially a sealed one, is not a museum or an area for free walks," Karchaa told Russia's RBC news outlet.

"While in 'sealed' mode, personnel access to the containment shells is prohibited and is only permitted with unambiguous justification and in emergency cases," he added.

IAEA chief Rafael Grossi had said in a statement Wednesday that experts had not been allowed to access reactor halls in three of the plant's units for two weeks.

He said the IAEA would continue to request access to the reactor halls, where the reactor core and spent fuel are located.

"The content of the latest statement gives us reason to assume that either Rafael Grossi was not informed fully enough, or the information was submitted by people with low professional training, which is hard to believe," Karchaa said.

The plant stopped supplying electricity to Ukraine's grid in September 2022, and has been repeatedly rocked by shelling and drone attacks throughout the conflict.