Drones attacked Zaporizhzhia, Europe's biggest nuclear power plant, on Sunday, hitting a reactor building in the worst such incident since November 2022 although nuclear safety was not compromised, the International Atomic Energy Agency has said.

Russia and Ukraine have repeatedly accused one another of targeting the plant since Russia seized it weeks after it invaded Ukraine.

Both countries requested an emergency meeting of the IAEA's board soon after Sunday's attack.

"The most recent attacks ... have shifted us into an acutely consequential juncture in this war," IAEA director general Rafael Grossi said in a statement to the board gathering.

The drone attacks on the plant were "significantly increasing the risk of a nuclear accident," he said.

He called on the board "unanimously to support the role of the IAEA in monitoring" principles aimed at preventing an accident at the plant, including that it not be attacked.

Since no draft resolutions have been submitted to the board meeting, it is likely to boil down to an exchange of statements by the countries convening behind closed doors in Vienna.

"We are meeting today, and I will meet with the UN Security Council next week, because it is of paramount importance to ensure these reckless attacks do not mark the beginning of a new and gravely dangerous front of the war," Grossi said, adding: "Strikes must cease".

Representatives of Russia and Ukraine, who were in attendance at the meeting, once again blamed each other for the attacks.

Grossi, however, avoided apportioning blame.

On Sunday, the nuclear power plant was attacked by drones in three places, according to IAEA observers.

The dome of a reactor and targets in the immediate vicinity of reactor buildings were hit.

No serious structural damage was sustained but one person was reported injured.

The observers also reported shots fired by Russian forces stationed at the nuclear power plant.

Ukrainian officials said Russian missiles and drones destroyed a large electricity plant near Kyiv and hit power facilities in several regions of the country on Thursday.

The major attack completely destroyed the Trypilska coal-powered thermal power plant near the capital, a senior official at the company that runs the facility told Reuters.

Footage shared on social media showed a fire raging at the large Soviet-era facility and black smoke belching from it.

"We need air defence and other defence support, not eye-closing and long discussions," Ukrainian President Volodymyr Zelenskiy said on Telegram, condemning the attacks as "terror".

President Vladimir Putin said on Thursday that Russia had been obliged to launch strikes that have inflicted heavy damage on Ukrainian energy sites in response to Ukrainian attacks on Russian targets.

The Kremlin leader, quoted by Russian news agencies, was speaking to ally Belarusian President Alexander Lukashenko.

Putin said the strikes were part of the process of "demilitarisation" of Ukraine - one of the objectives he cited when he sent Russian troops into Ukraine in February 2022.

"Unfortunately, we observed a series of strikes on our energy sites recently and were obliged to respond," Putin was quoted as saying.

"The strikes on energy are linked in part with solving one of the tasks we set for ourselves, and that is demilitarisation. We believe above all that in this way we will affect Ukraine's military industrial complex and in a very direct way."

"The situation in Ukraine is dire; there is not a moment to lose," said US ambassador Bridget Brink, adding that 10 missiles struck infrastructure in the Kharkiv area alone.

The grid operator issued a statement urging Ukrainians to minimise their use of electricity in the peak evening hours.

with DPA

Australian Associated Press