The UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), condemned a Ukrainian drone strike at one of six reactors at the Russian-controlled Zaporizhzhia Nuclear Power Plant in Ukraine, saying that such attacks "significantly increase the risk of a major nuclear accident."

In a statement on X, IAEA Chief Rafael Mariano Grossi confirmed that at least three direct hits occurred on the plant's main reactor containment structures.

"This cannot happen," he said. "As I said before the UN Security Council and the IAEA Board of Governors, no one can conceivably benefit or get any military or political advantage from attacks against nuclear facilities."

Grossi said that the attack was the first since November 2022, a time when he set out five basic principles to avoid a serious nuclear accident with radiological consequences.

The Associated Press cited plant officials who said the attack happened on Sunday, Apr. 7, when Ukrainian military drones struck the plant, including the dome of its sixth power unit.

Plant authorities added that there was no critical damage or casualties, and radiation levels at the plant remained normal after the strike.

However, Russian state-owned nuclear agency Rosatom said late Sunday that three people were wounded in the "unprecedented series of drone attacks," specifically when a drone hit an area close to the site's canteen.

The IAEA added that its experts had been informed of the drone strike and that "such detonation is consistent with IAEA observations."

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"Damage at unit 6 has not compromised nuclear safety, but this is a serious incident with the potential to undermine integrity of the reactor's containment system," it added.

The plant was caught in the crossfire when Russian troops invaded Ukraine in 2022 and seized the facility shortly after that. The IAEA 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—and the Kakhovka Dam that supplied it with vital water from the Dnipro to cool its reactors. The plant has been shut down for months but still needs power and qualified staff to operate crucial cooling systems and other safety features.

"I firmly appeal to military decision makers to abstain from any action violating the basic principles that protect nuclear facilities," Grossi concluded his statement.

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