Russian soldiers who seized the site of the Chernobyl nuclear disaster drove their armored vehicles without radiation protection through a highly toxic zone called the "Red Forest," kicking up clouds of radioactive dust, workers at the site said.

The two sources said soldiers in the convoy did not use any anti-radiation gear. The second Chernobyl employee said that was "suicidal" for the soldiers because the radioactive dust they inhaled was likely to cause internal radiation in their bodies.

Ukraine's state nuclear inspectorate said on Feb. 25 there had been an increase in radiation levels at Chernobyl as a result of heavy military vehicles disturbing the soil. But until now, details of exactly what happened had not emerged.