Georgia has accused Moscow of building up its forces and holding “unprecedented” war games in disputed territories as Russia warned of a "terrible conflict" if Nato allows the former Soviet republic to join.

The sabre-rattling came on the 10th anniversary of the Russian invasion, which deprived Georgia of one-fifth of its territory.

The foreign affairs ministry in Tbilisi said Russia was conducting large-scale military drills involving thousands of troops and hundreds of vehicles in the breakaway regions of Abkhazia and South Ossetia.

It called the operations an “unprecedented attempt by Russia to demonstrate its military power” and threaten Georgia, a tiny Caucasian country sandwiched between Russia and Turkey on the Black Sea.

In the decade since the conflict, Moscow has failed to implement the ceasefire agreement brokered by the EU and “has further reinforced its illegal military presence on the ground”, it said.

The five-day war began when Georgia shelled separatists in South Ossetia, giving Russian forces a pretext to pour over the border and cement control of the two breakaway regions, which seceded in the 1990s.

Allies including the United States refrained from intervening. Only Russia and a handful of countries recognise South Ossetia and Abkhazia as independent.

“We shouldn't be afraid to call things by their names. What Russia did and is doing against a sovereign government is a war between Russia Georgia, it's aggression, it's an occupation and it's a violation of all international norms,” president Giorgi Margvelashvili told ministers from Poland, Lithuania, Latvia and Ukraine at a meeting in the capital Tbilisi.