Ukraine's nuclear power company said on Friday the Russian-occupied Zaporizhzhia nuclear power plant, which requires constant external power to prevent a disaster, was on the verge of a blackout after Russia struck a nearby hydro-electric dam, Ednews reports citing Reuters.

Europe's largest nuclear power plant, which was captured by Russian forces shortly after their invasion in 2022, is shut down and needs external power to keep its nuclear material cool and prevent a catastrophic meltdown. It is near Ukraine's biggest hydro-electric dam, which was hit by major Russian strikes on Friday, causing blackouts across central Ukraine.

The International Atomic Energy Agency said the nuclear power plant had lost connection to its main off-site power line, but that a backup power line was still working.

"Such a situation is extremely dangerous and threatens to lead to an emergency," Petro Kotin, head of Ukraine's Energoatom nuclear power company, said on the Telegram messenger.

"If the last remaining line linking the facility to the national power grid is disconnected, (the plant) will get into another blackout, which is a serious violation of the conditions for the safe operation of the plant," he said.

The plant has been cut off from power several times during the war and has in the past been forced to rely on backup diesel generators, which officials say poses an increased risk of nuclear accident.

The Russian-controlled management of the plant said earlier that one of the two high-voltage lines supplying it with electricity was down but that there was no safety threat.