The operator of the Chernobyl nuclear plant announced on Wednesday that Russian forces disconnected the facility's power grid.
Ukrenergo, the Ukrainian state-owned grid operator, wrote in a Telegram post that there is "no possibility" of restoring the lines because of Russia's military action in the country.
"Because of military actions of Russian occupiers the nuclear power plant in Chornobyl was fully disconnected from the power grid. The nuclear station has no power supply," Ukrenergo wrote.
"The military actions are in progress, so there is no possibility to restore the lines," the company added.
While it is now closed, the Chernobyl plant requires electricity for cooling, ventilation and fire extinguishing systems, according to The Washington Post.
Ukrenergo wrote in a Facebook post on Wednesday that emergency diesel generators onsite to supply power to critical systems have been turned on, though the fuel is only enough for 48 hours.
The director general of the International Atomic Energy Agency, the United Nations nuclear watchdog, wrote in a statement on Tuesday that "remote data transmission from safeguards monitoring systems installed at the Chornobyl NPP had been lost."
"The Agency is looking into the status of safeguards monitoring systems in other locations in Ukraine and will provide further information soon," the organization added.
Ukrainian Foreign Minister Dmytro Kuleba is now calling for a cease-fire from Russia to allow repair units to rectify issues at the plant.
"The only electrical grid supplying the Chornobyl NPP and all its nuclear facilities occupied by Russian army is damaged. CNPP lost all electric supply," Kuleba wrote on Twitter on Wednesday.
"I call on the international community to urgently demand Russia to cease fire and allow repair units to restore power supply ... Reserve diesel generators have a 48-hour capacity to power the Chornobyl NPP," Kuleba added in a separate tweet. "After that, cooling systems of the storage facility for spent nuclear fuel will stop, making radiation leaks imminent."
The foreign minister said Russian President Vladimir Putin's "barbaric war puts entire Europe in danger," adding, "He must stop it immediately."