Russia's main security service has detained a Russian army officer on suspicion of spying for Georgia, a spokesman said.

The officer, an ethnic Georgian identified as Mikhail Khachidze, was detained in the southern Russian region of Stavropol near Georgia, said a spokesman for the FSB, the successor service to the Soviet-era KGB.

"(He) was involved in collecting secret information on Russian armed forces, its combat readiness as well as data on other servicemen," he said.

The conflict between Georgia and Russia erupted after Tbilisi tried to recapture the Moscow-backed separatist region of South Ossetia. This triggered a Russian counter-attack that has shaken ties between Moscow and the West.

Russia this week accused Georgia this week of plotting terrorist attacks in Russia and stepped up security at strategic locations, an allegation dismissed as nonsense by Tbilisi.

Georgia says around 200 Georgians, not including South Ossetians, died during the fighting that started on Aug 7. Russia says 1,600 people, mainly civilians, were killed. The figures have not been independently verified.