The decommissioned Chernobyl nuclear plant, site of the world’s worst nuclear disaster, has been knocked off the power grid, Ukrainian authorities say.
Emergency generators are now supplying back-up power.
The outage could put systems for cooling nuclear material at risk, the state communications agency said.
The cause of the damage to the power line serving Chernobyl was not immediately clear, but it comes amid Russia’s invasion of Ukraine.
The site has been under control of Russian troops since last week.
Ukrainian grid operator Ukrenerho said that, according to the national nuclear regulator, all Chernobyl facilities are without power and the diesel generators have fuel for 48 hours.
Without power the “parameters of nuclear and radiation safety” cannot be controlled, it said.
Foreign minister Dmytro Kuleba said the grid supplying electricity is damaged and called for a cease-fire to allow for repairs.
Radiation leaking
France has said it is in contact with the International Atomic Energy Agency (IAEA) as it seeks to assess the situation at Ukraine's Chernobyl nuclear power plant, government spokesman Gabriel Attal said on Wednesday.
"We are trying to clarify these reports together with the International Atomic Energy Agency," said Attal, who added that France was asking Russia to co-operate.
Meanwhile, a German environment ministry spokesperson had said on Wednesday that Germany had no knowledge of radiation leaking from the Chernobyl nuclear power plant in Ukraine.
French president Emmanuel Macron had urged Russian president Vladimir Putin to ensure the protection and security of Ukraine's nuclear sites, during talks between the two over the weekend.
