Georgia has today accused Russia of shooting down an unmanned Georgian reconnaissance plane in an "act of international aggression", but Moscow hit back by saying Georgia was deliberately fanning tensions.
The crisis between the ex-Soviet neighbours came two weeks after NATO promised Georgia it would one day be allowed to become a member, angering Moscow, which is fiercely opposed to the alliance drawing closer to its borders.
Georgian President Mikhail Saakashvili said he had had a heated telephone conversation with his Russian counterpart Vladimir Putin after Tbilisi released video footage that it said showed a Russian MiG-29 fighter shooting down the drone.
Georgian officials said the incident happened over Abkhazia, a breakaway Georgian territory on the Black Sea coast that is a constant source of friction between Tbilisi and Moscow.
"This is an act of international aggression. This is bombardment of a sovereign state by another state without any provocation or legal basis," Saakashvili, a U.S.-educated lawyer, said on national television after talking to Putin.
Russia's air force dismissed the allegations over the drone as "nonsense".
Putin later went on the attack, saying that he had told Saakashvili of his "bewilderment" that Georgia was sending drones over Abkhazia.
"This is a destabilising factor escalating tension," a statement from the Kremlin said.
Georgia, a state of about 5 million people in the Caucasus mountains, has become the focus for a broader tussle between Russia and the West for influence in the region, a transit route for oil from the Caspian Sea.
Abkhazia is internationally recognised as part of Georgia but, since a war in the 1990s, it has been run by separatists with backing from Moscow.
Most of its population are ethnically distinct from Georgians. They say they were forcibly absorbed into Georgia under Soviet rule and want to exercise their right to self-determination. Most of the residents have been issued with Russian passports, and most of their trade is with Russia.
Tbilisi last week accused Moscow of a de facto annexation of Abkhazia and a second breakaway Georgian region, South Ossetia, after Putin ordered his government to establish closer ties with the separatists in both regions.
Monday's crisis began when Georgia's air force released video footage which it said had been taken by the reconnaissance plane's on-board camera moments before it was shot down.
Abkhazia's separatist administration had said on Sunday that its forces had shot down the drone because it was violating Abkhaz air space.