The UN's atomic watchdog agency confirmed the "physical impact of drone attacks" on one of the six nuclear reactors at the site on Sunday.

The "serious incident" had the "potential to undermine (the) integrity of the reactor's containment system", the International Atomic Energy Agency (IAEA) said, adding that one casualty was reported.

"Such reckless attacks significantly increase the risk of a major nuclear accident and must cease immediately," said Rafael Mariano Gross, director general of the IAEA.

He added it was the first such attack since November 2022.

According to the Russian plant officials, radiation levels were normal after the strikes.

Russia's nuclear power corporation Rosatom accused Ukraine's military of launching the attacks on the plant.

Ukraine denied any involvement in the incident and suggested Russia was to blame.

"Ukraine is not involved in any kind of armed provocations on the territory of the Zaporizhzhia nuclear power plant illegally occupied by Russia," Andriy Yusov, a spokesperson for Ukraine's main directorate of intelligence, said.

"Russian strikes, including imitation ones, on the territory of the Ukrainian nuclear power plant....have long been a well
known criminal practice of the invaders."

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The power plant has been in the crossfire since Russia invaded Ukraine in 2022 and rapidly seized the facility.

The IAEA has repeatedly expressed alarm about the nuclear power plant, Europe's largest, amid fears of a potential nuclear catastrophe.

Both Ukraine and Russia have regularly accused the other of attacking the plant, which is still close to the frontlines.

The plant's six reactors have been shut down for months, but it still needs power and qualified staff to operate crucial cooling systems and other safety features.