Kiev, Ukraine ? Ukrainian authorities found radioactive material believed stolen from the now-defunct Chernobyl nuclear power plant a decade ago, an official said Wednesday.

Security officers discovered a plastic bag with 14 pieces of nuclear fuel during a routine search of the damaged reactor’s perimeter last week, said plant spokesman Stanislav Shektela. The pieces included part of a fuel rod and small pipes.

He said the radioactive material “was probably missing since 1995,” when a group of people was arrested and convicted of stealing nuclear fuel from the destroyed reactor’s central hall.

Experts are now trying to positively identify the material while police investigate, Shektela said.