THESSALONIKI, Greece (AP) -- A small amount of plutonium believed smuggled from Eastern Europe was found buried in a park, in a possible sign of increased trafficking of radioactive material, officials said Tuesday.

Metal plates containing about a tenth of an ounce of plutonium and americium, another radioactive element, were found Saturday by Finance Ministry agents acting on a tip.

The ministry's fraud agency is investigating possible link between the plutonium and a cigarette smuggling ring from neighboring Bulgaria, police sources said. The park where the plutonium was found is about 7 1/2 miles outside Thessaloniki, and is often used for picnics and by joggers.

The amount was far less than the plutonium needed to make a bomb. But it raises concern of toxic contamination from the highly dangerous substances.

About 20 pounds of plutonium are used in a bomb, according to U.S. government estimates. But other experts say just over half that amount is needed.

"Plutonium is usually sold for terrorism purposes," said the agency's director, Leonidas Kamarinopoulos. "Plutonium is very dangerous even in this quantity."

The plates were transported to a safe facility in Athens by members of the state Agency of Atomic Energy, authorities said. Greece has only one small nuclear reactor used for research.

Kamarinopoulos said the find had been reported to the International Atomic Energy Commission in Vienna, Austria, which will try and trace its origin. The plutonium will be transported to its country of origin or one which processes radioactive materials for power generation, he said.

Greece has become a crossroads for various kinds of smuggling, including trafficking in drugs and illegal weapons.