The attacks "marked a major escalation of the nuclear safety and security dangers in Ukraine," Rafael Grossi of the International Atomic Energy Agency (IAEA) said in Vienna.

He spoke at an emergency meeting of the 35 members of the Board of Governors, called by both Russia and Ukraine.

The Zaporizhzhia plant (ZNPP), which Russia has occupied since March 2022, has been hit by a series of drone attacks since Sunday, with Moscow and Kyiv each accusing the other.

They were the first attacks since November 2022 on the plant -- once the largest nuclear power station in Europe but which now is not in operation.

"There should be no attack of any kind from or against the plant, in particular targeting the reactors, spent fuel storage, other critical infrastructure, or personnel," Grossi said.

After the three-and-a-half hour meeting broke up, Russian ambassador to the IAEA Mikhail Ulyanov said it was a "useful meeting" and he "hope(d) that today's discussion will help the Ukrainian side to stop these dangerous actions".

Ukraine, on the other hand, denounced a "disinformation campaign" by Moscow, saying in a communique from its permanent mission in Vienna that Russia was simulating attacks to "discredit" Ukraine.

The European Union said in its statement to the meeting that "the latest alarming developments... underscore that Russia's illegal seizure of the plant significantly increases risks to nuclear safety".

"Russia must unconditionally, immediately and completely withdraw all its forces and military equipment from the ZNPP and the whole territory of Ukraine," it said.

Since the start of Russia's invasion of Ukraine in 2022, the IAEA's board of governors has adopted four resolutions condemning Russian actions at the plant.