Ukraine accused Russian forces over the weekend of launching rockets at the Zaporizhzhia nuclear power plant, further stoking fears of an accident a day after the United Nations atomic energy watchdog warned that fighting at the six-reactor complex risked a “nuclear disaster.”

It was the second time in as many days that the plant, which is the largest of its kind in Europe, was hit. Ukraine and Russia have traded blame for both attacks.

The rockets launched on Saturday night struck near a dry storage facility, where 174 casks with spent nuclear fuel are kept, according to Energoatom, Ukraine’s state-run nuclear power company. Explosions blew out windows in parts of the plant and one worker was hospitalized with shrapnel wounds.

“Apparently, they aimed specifically at the containers with processed fuel, which are stored outside next to the site of shelling,” Energoatom’s statement on Telegram on Telegram read.

Three radiation monitoring detectors were also damaged on Saturday, making “timely detection and response in case of aggravation of the radiation situation or leakage of radiation from spent nuclear fuel casks are currently impossible,” Energoatom said.

“This time a nuclear catastrophe was miraculously avoided, but miracles cannot last forever,” it added.

Kyiv has accused Russian forces of storing heavy weaponry in and launching attacks from the plant, which they took over in early March and still occupy. Moscow, meanwhile, has claimed Ukrainian troops are targeting the complex.

The head of the pro-Russian regional administration in Zaporizhzhia, Yevgeny Balitsky, said in a statement on Telegram Sunday that Ukrainian forces had targeted the spent fuel storage area and damaged administrative buildings.

Fears about the security of Zaporizhzhia nuclear plant have been growing since Russian forces seized the site on March 4. Those fears intensified on Friday when shelling damaged a high-voltage power line and forced one of the plant’s reactors to stop operating — though no radioactive leak was detected.

Petro Kotin, head of Ukraine’s state nuclear power company Energoatom, called for a team of peacekeepers to be deployed at the Zaporizhzhia site.

“The decision that we demand from the world community and all our partners … is to withdraw the invaders from the territory of the station and create a demilitarised zone on the territory of the station,” Kotin said on television in remarks reported by Reuters.

“The presence of peacekeepers in this zone and the transfer of control of it to them, and then also control of the station to the Ukrainian side would resolve this problem.”

After Saturday’s attack, Energoatom said that Russian shellfire had damaged a nitrogen-oxygen station and the combined auxiliary building, and that there were “still risks of hydrogen leakage and sputtering of radioactive substances, and the fire hazard is also high.”

The fighting, along with Russia’s occupation of parts of the plant and the stress borne by plant workers, prompted Rafael Grossi, the head of the International Atomic Energy Agency, the United Nations’ nuclear watchdog, to warn last week that “every principle of nuclear safety has been violated.”

Conditions at the plant are “out of control,” he added in an interview with The Associated Press on Tuesday.

So far, there are no reports of a radiation leak at Zaporizhzhia. But the prospect of a Ukrainian counteroffensive to reclaim land in Kherson Province, which is southwest of Zaporizhzhia, heightens the instability surrounding the plant.

Ukraine was the site of the world’s worst nuclear accident, the 1986 reactor explosion at Chernobyl in the country’s north, which spread radiation throughout the region and put Europe at risk.

Russian forces held, but later abandoned, the Chernobyl site in the early weeks of the war. But Gross said in his interview that he is far more worried about Zaporizhzhia, noting that while his agency had been able to restore sensors and resume regular inspections at Chernobyl, the Russian occupation and continued shelling at Zaporizhzhia had prevented the watchdog from accessing key parts of its reactors.

The Russian occupation of the plant has put its employees under intense pressure according to Energoatom and numerous Western media reports, as Russian forces hunt for saboteurs among the workforce and subject them to harsh interrogations, Ukrainian officials assert. Dmytro Orlov, the exiled mayor of the plant’s host city, Enerhodar, has said that some workers have disappeared and that at least one was killed.