Georgia has accused Russian troops of illegally entering its territory, amid a continuing escalation of tensions between the two countries.

Abkhaz separatists won de facto independence in a 1992-93 war

Georgia said Russian troops had crossed into the disputed Kodori gorge in western Georgia with troops from the breakaway region of Abkhazia.

Both Russia and Abkhazia denied the allegation.

For its part, Russia has accused Georgia of providing a base for Chechen rebels and has not ruled out a military operation against the rebels.

The BBC's Stephen Dalziel in Moscow says as the war of words between Russia and Georgia becomes hotter, the dangers of it spilling over into armed conflict are growing.

Simmering conflict

Georgia and Abkhazia have been in a state of suspended conflict since 1993, when Abkhaz separatists, backed by Russian forces, succeeded in driving the Georgian army out of the province.

The Kodori Gorge is a lawless area, nominally still under Georgian control, though within the boundaries of the semi-autonomous Abkhaz region that existed within Georgia until the early 1990s.

Georgia' envoy to Abkhazia Emzar Kvitsiani said a Georgian helicopter came under fire on Sunday during a reconnaissance mission after the reported incursion.

But the vice-President of Abkhazia, Valery Arshba, denied the allegation and blamed Georgia for violating Abhkazia's air space.

"A warning shot was made. If there will be another such case, we'll shoot it down."

Our correspondent says Russia claims to be the peacekeeper in the region, but Tbilisi has long maintained that Moscow is merely defending its own interests there.

Russia unmoved

The incident came only days after Georgia accused Russia of sending combat aircraft to raid its territory, on the pretext of attacking Chechen rebels in the remote Pankisi Gorge.

Georgia said the Russian attacks amounted to aggression against a neighbouring sovereign state.

Russia denied the allegations, and in turn accused Georgia of failing to fight terrorism.

Moscow also warned that it may consider using a military force to deal with the rebels on Georgia's territory.

The Russian Defence Minister, Sergei Ivanov, blamed Georgia of going back on an agreement three years ago to allow Russian troops to pass from Georgia to reinforce their common border in the region of Chechnya.

The tension is escalating just as US Army officers in Georgia prepare to train Georgian troops to fight international terrorism.