The Friday strikes on the Zaporizhzhia nuclear plant in south Ukraine -- Europe's largest atomic power complex -- "seriously damaged" a station containing nitrogen and oxygen and an "auxiliary building," Energoatom said on the Telegram messaging service.

Kyiv and Moscow blamed each other for the attacks.

The strikes had damaged a power cable, forced one of the reactors to stop working and "there are still risks of leaking hydrogen and radioactive substances, and the risk of fire is also high," it said.

The shelling "has caused a serious risk for the safe operation of the plant."

Russian troops have occupied the Zaporizhzhia plant since the early days of their invasion and Kyiv has accused them of storing heavy weapons there.

But Moscow, in turn, has accused Ukrainian forces of targeting the plant.

The European Union hit out at Russia on Saturday over the shelling.

"The EU condemns Russia's military activities around #Zaporizhzhia nuclear power plant," the bloc's top diplomat, Josep Borrell, wrote on Twitter.

"This is a serious and irresponsible breach of nuclear safety rules and another example of Russia's disregard for international norms."

Borrell insisted that the UN's nuclear watchdog, the International Atomic Energy Agency, be given access to the plant.

The IAEA has been trying for weeks to send a team to inspect the plant. Ukraine has so far rejected the efforts, which it says would legitimise Russia's occupation of the site in the eyes of the international community.

It said employees of Russian nuclear operator Rosatom had left the plant shortly before the attacks but that Ukrainian personnel had stayed on and the plant was still generating electricity.

Ukraine President Volodymyr Zelensky had said on Friday that "any bombing of this site is a shameless crime, an act of terror."

And the Ukrainian foreign ministry had said that the "possible consequences of hitting a working reactor are equivalent to using an atomic bomb".

Earlier in the week the IAEA said that the situation at the nuclear power plant was "volatile."

"Every principle of safety has been violated one way or the other," IAEA chief Rafael Grossi said.