CHISINAU -- Police in Moldova have announced the arrests of seven men suspected of smuggling nuclear material from Russia.
General Police Inspectorate Chief Ion Bodrug said on December 9 that the men are charged with importing, storing, and selling nuclear materials. He said the materials could be used to make a crude radioactive explosive device, known as a dirty bomb.
Bodrug says police confiscated 200 grams of uranium 238 mixed with uranium 235, one kilogram of mercury, and an unidentified solid radioactive material after searches and raids last week in Chisinau and two other Moldovan cities.
WATCH: Video of one of the raids, provided by the Moldovan General Police Inspectorate
The confiscated materials, which allegedly were transported to Moldova from Russia by train, reportedly have a black market value of $2 million.
FBI agents from the United States assisted Moldovan authorities in an investigation that started in January 2014.
Authorities say one undercover police officer involved in the investigation managed to infiltrate a criminal group involved in the smuggling operation..
Bodrug said those arrested range in age from 32 to 75 and that some have specialized knowledge about radioactive substances.
Moldovan authorities said they were cooperating with Ukrainian and Russian police to identify other gang members.
Uranium 235 is fissile and uranium 238 can be enriched to a level of fissile material, meaning it can be used to sustain a nuclear chain reaction, leading to applications in nuclear weapons and nuclear reactors.
Uranium 238 also can be converted into plutonium, which is used for nuclear weapons.
With reporting by AP