Georgian soldiers have been arrested in South Ossetia as tensions have risen
US Secretary of State Condoleezza Rice has arrived in Georgia amid an escalating row between Russia, Georgia and the United States.
Russia accused Georgia of bringing the South Caucasus to the brink of armed conflict - comments which both Ms Rice and Nato condemned as "unhelpful".
Georgia and Russia also accused each other of flying jets over Georgia's breakaway region of South Ossetia.
Flights over the territory were outlawed by a ceasefire deal.
Ms Rice is visiting Georgia at a time when tensions in its breakaway regions of South Ossetia and Abkhazia are higher than they have been for many months, says the BBC's Matthew Collin, in the capital Tbilisi.
Russia, which backs the separatist governments in both regions, has accused Georgia of being behind a deadly cafe bomb in Abkhazia and clashes with South Ossetian separatists.
The Russian foreign ministry said on Wednesday that: "Tbilisi's actions represent a real threat to peace and security... capable of taking the region to the brink of a new armed conflict with unpredictable consequences."
But Ms Rice said before her arrival in Georgia that Russia had made "a number of moves... that in fact have not been helpful in terms of the frozen conflicts there".
Moscow reinforced its peacekeeping force in Abkhazia earlier this year, and established semi-official ties with the separatists.
Nato Secretary-General Jaap de Hoop Scheffer also reacted strongly to Russia's comments, saying: "This is unhelpful rhetoric that will not bring parties closer."
And Georgian Foreign Minister Eka Tkeshelashvili said Russia was "deliberately escalating" tensions in Georgia's separatist regions.
On Wednesday Georgia accused Russia of violating its airspace.
"For almost 40 minutes, four Russian planes were circling over the territory north of Tskhinvali," the main city in South Ossetia, the deputy commander of Georgia's air force, Colonel Zurab Pochkua, said.
The accusations were turned around by Russia. A spokesman for Russian peacekeeping forces in South Ossetia said two Georgian Su-25 fighter jets flew over the region - "a serious breach" of the flight ban that has been in place since a ceasefire ended the separatist conflict that broke out after the collapse of the Soviet Union.