The “alarming” situation at a Russian-occupied nuclear power plant in southeastern Ukraine had reached a “grave hour,” the head of the United Nations' nuclear watchdog said Thursday, as he called for an immediate inspection of the facility by international experts.

International Atomic Energy Agency (IAEA) Director General Rafael Mariano Grossi warned that parts of the Zaporizhzhia nuclear plant had been knocked out due to recent attacks, risking an “unacceptable” potential radiation leak.

“IAEA experts believe that there is no immediate threat to nuclear safety,” but “that could change at any moment,” Grossi said.

“Any military action jeopardizing nuclear safety, nuclear security, must stop immediately,” he added. “These military actions near to such a large nuclear facility could lead to very serious consequences.”

The Zaporizhzhia facility -- the largest nuclear plant in Europe -- occupies an extensive site on the Dnipro River near the Russian-occupied city of Enerhodar. It has continued operating at reduced capacity since Russian forces captured it early in March, with Ukrainian technicians remaining at work.

Russia and Ukraine have so far been unwilling to agree to an IAEA inspection of the plant and have accused each other of shelling the facility -- action the IAEA has said breaches “indispensable nuclear safety and security pillars.”

Russia's UN Ambassador Vassily Nebenzia on Thursday blamed Ukraine for the shelling and urged Kyiv's supporters to stop attacks and prevent a disastrous radiation leak.

But Ukrainian President Volodymyr Zelensky pointed the finger at Moscow, which he said was putting all of Europe in danger.

“Only the complete withdrawal of Russians from the territory of the Zaporizhzhia NPP and the restoration of Ukraine's full control over the situation around the plant will guarantee the restoration of nuclear safety for all of Europe,” Zelensky said.

Ukraine's nuclear agency Energoatom said 10 shells landed near the complex on Thursday, preventing a shift handover.

“For the safety of nuclear workers, the buses with the personnel of the next shift were turned back to Enerhodar,” the agency said. “Until the situation finally normalizes, the workers of the previous shift will continue to work.”

Energoatom said radiation levels at the site remained normal, despite renewed attacks.

Several Western and Ukrainian officials believe that Russia is using the giant nuclear facility as a stronghold to shield their troops and mount attacks, because they assume Kyiv will not return fire and risk a crisis.

US Secretary of State Antony Blinken has accused Moscow of using the plant to shield its forces, while Britain's Defense Ministry said in a recent security assessment that Russia's actions at the complex sabotage the safety of its operations.

The Ukrainian mayor of Enerhodar, Dmytro Orlov, said in late July that Russian forces had been observed using heavy weaponry near the plant because “they know very well that the Ukrainian Armed Forces will not respond to these attacks, as they can damage the nuclear power plant.”

The US on Thursday backed Ukraine's calls for a demilitarized zone around the facility, while at the UN, Bonnie Jenkins, US undersecretary for arms control and international affairs, said Russia is responsible for the “nuclear risks” at the plant.

She warned the UN Security Council that “the many consequences of this conflict, including the situation at the Zaporizhzhia nuclear power plant, will only end when Russia ends its war.”

UN Secretary General Antonio Guterres -- who previously called shelling at the plant “suicidal” -- on Thursday, said in a statement he was “gravely concerned.”

“We must be clear that any potential damage to Zaporizhzhia or any other nuclear facilities in Ukraine, or anywhere else, could lead to catastrophic consequences not only for the immediate vicinity, but for the region and beyond,” he said. (CNN)

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