Moscow and Kyiv traded fresh accusations on Saturday of shelling around the Russian-controlled Zaporizhzhia nuclear power plant in Ukraine, which has been a focus of international concern that fighting in the area could trigger a disaster.

Zaporizhzhia, Europe’s largest nuclear power plant, has been controlled by Russian forces since early March. Ukrainian staff continue to operate it and in recent weeks the two sides have traded blame for shelling near the plant.

Ukraine’s state nuclear company Energoatom energy agency said Russian troops again shelled the grounds of the plant complex in the last 24 hours, Reuters reported

“The damage is currently being ascertained,” Energoatom wrote in a statement on Telegram.

Moscow’s defense ministry accused Ukrainian forces of shelling the plant complex three times in the last 24 hours. Reuters could not verify the battlefield report.

“A total of 17 shells were fired, four of which hit the roof of Special Building No. 1, where 168 assemblies of US WestingHouse nuclear fuel are stored,” the Russian defense ministry said in a statement.

It said 10 shells exploded near a dry storage facility for spent nuclear fuel and three more near a building that houses fresh nuclear fuel storage. It said the radiation situation at the plant remained normal.

Ukraine’s President Volodymyr Zelenskiy said on Friday the situation at Zaporizhzhia remained “very risky” after two of its six reactors were reconnected to the grid following shelling that caused the nuclear plant to be disconnected for the first time in its history.

Energoatom said on Friday evening that both of the plant’s two functioning reactors had been reconnected to the grid and were again supplying electricity after they were fully disconnected on Thursday.

The Russian ministry, in its daily briefing, also said it had destroyed a large ammunition depot in Ukraine’s Dnipropetrovsk region that had contained US-made HIMARS rocket systems and shells for M777 Howitzers.

The Russian Air Force shot down a MiG-29 aircraft in the eastern Donetsk region, the ministry said, and destroyed another six missile and artillery weapons depots in the Donetsk, Mykolaiv and Kherson regions.