Russian forces who occupied the Chernobyl nuclear plant stole radioactive substances from research laboratories that could potentially kill them, Ukraine's State Agency for Managing the Exclusion Zone has said.
Moscow's forces seized the defunct power plant on the first day of their invasion of Ukraine on 24 February.
They occupied the highly radioactive zone for over a month, before retreating on 31 March.
The agency said on Facebook that Russian soldiers pillaged two laboratories in the area.
It said the Russians entered a storage area of the Ecocentre research base and stole 133 highly radioactive substances.
"Even a small part of this activity is deadly if handled unprofessionally," the agency said.
Earlier this week, Ukraine's energy minister German Gulashchenko said Russian soldiers exposed themselves to a "shocking" amount of nuclear radiation, saying some of them may have less than a year to live.
"They dug bare soil contaminated with radiation, collected radioactive sand in bags for fortification, breathed this dust," Mr Gulashchenko said on Facebook on Friday after visiting the exclusion zone.
"After a month of such exposure, they have a maximum of one year of life. More precisely, not life but a slow death from diseases," the minister said.
"Every Russian soldier will bring a piece of Chernobyl home. Dead or alive."
He said Russian military equipment was also contaminated. "The ignorance of Russian soldiers is shocking," he added.
The Chernobyl power station was the site in 1986 of the world's worst nuclear disaster.