Vladimir Ivanov, an aide to the commander of the Joint Peacekeeping Forces in the Georgian-South Ossetian conflict zone, was quoted as saying that an aircraft was observed at 22:20 local time (18:20 GMT) on Tuesday evening.
An unmanned Georgian surveillance drone was shot down over Abkhazia on April 20. Georgia claimed the plane was downed by the Russian Air Force, calling it an act of aggression, while Russia denied involvement. A UN report in early June said that Russia was responsible for the downing of the drone. Moscow dismissed the report as based on unreliable evidence.
South Ossetia declared its independence from Georgia following the collapse of the Soviet Union in 1991. Hundreds died in the bloody conflict that followed. The pro-Western Georgian leadership has said it is determined to bring the region, along with another breakaway republic, Abkhazia, back under central control.
Both South Ossetia and Abkhazia have been the source of rising tensions between Georgia and Russia since Moscow stepped up support for the breakaway republics in April. Recent events have involved explosions and shootouts in Abkhazia as well as the brief arrest of Georgian officers by South Ossetia.
Earlier on Tuesday, the UN Security Council held a closed session to discuss an incursion into Georgian airspace by Russian military aircraft.
Georgia requested the session on July 10 in response to an admission by Russia on the same day that its fighters had flown over the breakaway Georgian territory of South Ossetia two days earlier.
Russia said it had carried out the flights over fears that Georgia could invade the republic. Tbilisi called the flights an act of "military aggression," and recalled its ambassador from Moscow.
South Ossetia rejected on Saturday an EU proposal to hold talks in Brussels on its current conflict with Georgia. A German peace plan for Abkhazia, backed by the EU, was rejected by the Abkhaz leader on Friday.
