INTERNATIONAL: Russian military forces have seized the Zaporizhzhia nuclear power plant ,Europe's largest, in Ukraine's southeast, the regional state administration said on Friday.

"Operational personnel are monitoring the condition of power units," it said on social media, quoting the Ukrainian nuclear inspectorate.

It has said efforts sought to ensure the operations were in line with safety requirements.

Ukraine has said Russian forces attacked the plant in the early hours of Friday, setting an adjacent five-story training facility on fire.

U.S. Energy Secretary Jennifer Granholm has said on Thursday the reactors at Zaporizhzhia power station "are protected by robust containment structures and reactors are being safely shut down".

Granholm has said she had spoken with Ukraine's energy minister about the situation at the plant. She has reported there was no elevated radiation readings near the facility.

Ukrainian emergency services has said one of six nuclear power units was working as of early Friday.

A volley of incoming shells, before a large candescent ball lit up the sky, exploding beside a car park and sending smoke billowing across the compound. It was not immediately clear who was in control of the plant.

Russia has already captured the defunct Chernobyl plant, about 100 km (62.1 miles) north of Kyiv, which spewed radioactive waste over much of Europe when it melted down in 1986. The Zaporizhzhia plant is a different and safer type, some analysts said.

Thousands of people are believed to have been killed or wounded and more than 1 million refugees have fled Ukraine since Russian President Vladimir Putin last Thursday launched the biggest attack on a European state since World War Two.