MOSCOW (AP) _ Russian authorities ordered a South Korean diplomat expelled Saturday after he was detained on suspicion of spying.

The diplomat, identified as Cho Seong-ho, was taken into custody overnight as he met with an alleged Russian contact, according to the Federal Security Service, a successor to the Soviet-era KGB.

The contact, an employee of Russia's Ministry of Foreign Affairs, was also detained, the statement said, accusing the Russian of spying for South Korea.

Cho, an advisor to the South Korean ambassador, has diplomatic immunity and was released after questioning, the statement said.

Later, the Foreign Ministry filed a formal complaint with the South Korean ambassador, ordering Cho to leave Russia within three days for ``illegal activities incompatible with his diplomatic status.''

A spokesman for the South Korean Embassy, Lee Sok-bae, confirmed that Cho had been detained and would be departing Russia. He declined to comment on the nature of the charges against the diplomat, or whether South Korea would take reciprocal action.

Russia's Federal Security Service, or FSB, is responsible for counterintelligence.