CHISINAU (Reuters) - Police in Moldova said on Tuesday they had detained seven people suspected of smuggling radioactive Uranium-238 on a train from Russia, a substance they said could have been used to make a "dirty bomb".
Police discovered about 200 grams (7 oz) of hazardous substances worth about 1.7 million euros ($2.1 million) during a sting operation last week, said Ion Bodrug, head of an Interior Ministry investigative department.
"After a preliminary examination we realized we were talking about Uranium-238, an extremely dangerous radioactive substance used to make 'dirty' nuclear bombs," he told a news conference.
A dirty bomb is not, in fact, a nuclear device and does not produce a nuclear explosion. Instead it mixes conventional explosives with radioactive material, with the aim of spreading contamination.
Another dangerous substance, mercury, was also discovered by the police, who believe the gang's aim was to sell the materials in Europe, Bodrug said.
The International Atomic Energy Agency is in "touch with Moldovan authorities regarding the case", senior IAEA official Serge Gas said in an email. He gave no further detail.
The Vienna-based United Nations agency has stepped up calls on member states to tighten security to prevent nuclear and radioactive materials from falling into the wrong hands.
The type of uranium used in atomic bombs is the U-235 isotope, which has three neutrons fewer than U-238 and is able to sustain a nuclear chain reaction, releasing massive energy.
The last known attempt to sell U-238 in Moldova was in August 2010 when police arrested three people from organized crime groups.
Last year, the IAEA said that more than 100 incidents of thefts and other unauthorized activities involving nuclear and radioactive material are reported by member states annually.
Because a dirty bomb would be relatively easy to make, security experts regard it as a more likely terrorist weapon than a nuclear bomb. They say such a device could trigger widespread panic, even if it did not cause major loss of life.
($1 = 0.8080 euros)
(Reporting by Alexander Tanas, additional reporting by Fredrik Dahl in Vienna; Editing by Mark Trevelyan)