Counter-intelligence and special operations units detained a Georgian and a foreign national while they were allegedly trying to sell radioactive uranium that "could be used to manufacture explosive devices or carry out terrorist attacks", the security services said.

The two men were seeking $3.0 million for the uranium when they were arrested in the Black Sea port city of Batumi, the services said.

The "nuclear material", described as a "radioactive chemical element emitting alpha and gamma radiation", was deemed capable of causing mass casualties if weaponised, the agency added.

It said the plot had been "detected and neutralised at an early stage".

The suspects face up to 10 years in prison for the illegal handling of nuclear material.

Concerns have existed for years that extremist groups could get hold of unsecured radioactive materials from countries across the former Soviet Union.

Georgia and neighbouring Armenia -- both ex-Soviet states -- have reported numerous cases of people trying to sell radioactive substances, including attempts to smuggle weapons-grade uranium.