Advisor to head of the President's Office of Ukraine Mykhailo Podoliak said Russian forces seized Chernobyl nuclear power plant (NPP), Interfax-Ukraine news agency reported.
"After a fierce battle, our control over the Chernobyl site has been lost," Podoliak said.
The condition of the facilities of the former Chernobyl nuclear power plant, confinement and storage of nuclear waste is unknown, he added.
"This is one of the most serious threats to Europe today," Podoliak emphasized.
The Chernobyl nuclear plant, some 110 km north of Kiev, witnessed one of the worst nuclear accidents in human history on April 26, 1986.