BRATISLAVA Slovak and Hungarian police seized a kilo (2.2 lbs) of radioactive material and arrested three people in a joint operation on Wednesday, a spokesman said.
Slovak police spokesman Martin Korch said the material was being examined and did not confirm a report carried by the Slovak news agency SITA that it was enriched uranium.
"This one kilogram should have been sold for one million U.S. dollars," Korch said.
Uranium enrichment can yield fuel for nuclear power stations or be used to make nuclear warheads. Uranium must be highly enriched to be suitable for use in weapons.
The spokesman said the police raid took place along the eastern part of the two central European countries' common frontier, near their borders with Ukraine.
"Three people have been taken into custody, two in Slovakia one in Hungary," he said, adding that further information would be released on Thursday.
The International Atomic Energy Agency (IAEA), a watchdog for the nuclear industry, says it has recorded 1,250 cases of smuggling and other crimes related to the handling of radioactive material since 1995.
Nuclear material is often smuggled from former Soviet Union.
Police in Slovakia's former federation partner, the Czech Republic, found 2.73 kg of high-enriched uranium in Prague in 1995, intended for illegal sale.
It was the second biggest ever seizure of high-enriched uranium after a 1994 find of 2.97 kg in Russia's St. Petersburg, according to the IAEA.
The last incident reported by the watchdog was a March, 2006 discovery of 47.5 grams of high-enriched uranium among scrap metal at a steel mill in Germany.
(Reporting by Martin Santa and Jan Lopatka; Editing by Matthew Tostevin)