The IAEA confirmed minor damage to the sixth power unit of the plant as a result of the drone attacks.
"This is a clear violation of the basic principles for protecting Europe’s largest [nuclear power plant]. Such reckless attacks significantly increase the risk of a major nuclear accident and must cease immediately," Grossi was quoted as saying in the IAEA statement.
Earlier in the day, Ukrainian kamikaze drones attacked the territory of the power station immediately after an inspection carried out by IAEA experts, the plant's press service said. The attack left three of the facility's workers injured, with one of them sustaining serious injuries, Russian state nuclear corporation Rosatom said.
The IAEA had previously confirmed damage to the plant in a separate statement. "IAEA experts confirmed physical impact of drone attacks at ZNPP today, incl. at 1 of its 6 reactors," the agency said. "One casualty reported. Damage at unit 6 has not compromised nuclear safety, but this is a serious incident with potential to undermine integrity of the reactor's containment system."
Russian Foreign Ministry spokeswoman Maria Zakharova said the international community must respond to Ukraine's attack, calling it "an act of nuclear terrorism."
"The world community must realize and react to an act of nuclear terrorism on the part of the Kiev regime," Zakharova said on Telegram.
The Zaporozhye nuclear plant, constructed in the 1980s by the Soviet Union, is Europe's largest and one of the world's largest. The massive power station is reportedly now completely reliant on a single 750-kilowatt line for external power after previous attacks. A connection to outside electricity is necessary to ensure the plant is able to cool its reactors – an interruption in the delivery of power could precipitate a catastrophic meltdown.
Russia took control of the sensitive asset in March 2022 and it has endured Ukrainian fire ever since. Ukrainian drones, missiles, and artillery have all been used against the plant by Kiev, which has repeatedly attempted to reassert control.
Kiev claims Russia is storing weapons at the power station and using it as cover to attack Ukrainian troops. Observers worry Ukraine may create a disaster at the plant, blaming Russia and spoiling newly-Russian territory. Kiev has repeatedly employed US-provided cluster munitions during fighting in the Donbass, raising the prospect of unexploded bomblets creating a hazard for decades to come.