The Chernobyl nuclear disaster site has seen a rise in radiation levels, according to the nuclear agency of Ukraine.
Ukrainian officials said that Russian troops seized the remnants of the Chernobyl nuclear plant.
Radiation levels went up at several points on and near the site.
The Verkhovna Rada, the parliament of Ukraine, posted a map showing radiation levels around Chernobyl increasing as of 6 a.m. local time Friday.
—Verkhovna Rada of Ukraine (@ua_parliament) February 25, 2022
According to the Center for Nuclear and Radiological Safety, radiation levels at multiple points appeared to be spiking.
Heavy military equipment moving through the area kicked up radioactive dust which caused the rise.
The radiation starts to increase. The interior ministry said that it is not critical for the time being.
Russia denied that there had been a change in radiation levels on Thursday, with state-run media saying they were normal as of 9 p.m.
The site of the worst nuclear disaster is Chernobyl. In 1986, a nuclear reactor blew up, spilling radioactive waste across eastern Europe.
There are fears that the plant could be compromised by the fighting, as it is surrounded by a 20-mile exclusion zone and secured under metal tanks.
If the invaders hit the collectors of nuclear waste, radioactive nuclear dust can be spread over the territory of Ukraine. An advisor to the interior ministry of Ukraine wrote on Facebook.
The exclusion zone is the most contaminated place on Earth, according to a radiation expert at the University of California at San Francisco.
Poland did not record an increase in radiation levels on Friday.
Several staff members at the Chernobyl site were taken hostage by Russian troops, according to a Thursday Facebook post by Alyona Shevtsova, an advisor to the commander of Ukraine's ground forces.
The White House said that the report was credible and that the US was angry.
The deputy prime minister for European and Euro-Atlantic integration of Ukraine said Friday that control over nuclear and radiation facilities was lost.
Russia lost Chernobyl at the end of the first day of its invasion of Ukraine.
Russian troops entered the country early Thursday morning and there were loud explosions throughout the day.
President Volodymyr Zelensky said Friday that his country has been left alone to defend itself from Russia.