Moscow/Tbilisi - President Mikhail Saakashvili said Thursday that Georgia had come "very close" to war with Russia and the "threat remained" for a breakout over its breakaway region of Abkhazia.

"If anyone wants to annex a part of Georgia, there will inevitably be consequences," Saakashvili told Russian journalists, though he stressed a desire to return to diplomacy.

Russia's military announced early Thursday that would increase its troops in Georgia's breakaway region of Abkhazia to counter Georgia's accumulating military forces in the contested region.

"All this is done for the sake of only one thing: preserving peace and avoiding bloodshed," read a statement by the defence ministry.

Frayed Georgian-Russian relations have long led to sparks in Abkhazia, the autonomy of which has been defended by Russian peacekeepers since a ceasefire ended a civil war in 1994.

But Moscow and Tbilisi's growing inclination to resort to action over their differences have ignited concerns in the European Union and the United States that the standoff is "close to war."

Russia's peacekeepers in Abkhazia will increase to 2,542 troops, under the maximum permitted of 3,000 as provided for by the UN ceasefire.

"The prolongation of the [peacekeepers'] mandate by the UN Security Council in April 2008 is a graphic confirmation of the need for a presence in the conflict zone," the ministry's statement said.

But Georgia's defence minister on Thursday denied his side had moved more troops to the border of the region.

"Georgia is not a country which went mad and decided to be engaged in a war with Russia," Defence Minister David Kezerashvili said.

"Georgia does not build up anything and does not build up anything near the conflict zones. All our soldiers are staying at their bases," he said.

Tensions have escalated over Moscow's security objection over its post-Soviet neighbour's bid to join NATO last month.

While Russia has long provided Abkhazia support and most citizens in the region hold Russian passports, Putin angered Tbilisi last month by announcing the start of formal diplomatic and economic ties with the Abkhaz government.

Georgia decried the move as the "de facto annexation" of its territory and called for international support.

The United States on Thursday came down in favour of Georgia's pro-Western government.

"Obviously we're very concerned what Russia is doing in Georgia, in a series of actions which we have labelled and said are provocative," said Stephen Hadley, a national security advisor to the US president.

"We think Russia needs to back down from those items," Hadley said.

The latest Russo-Georgian military accusations exploded when Tbilisi accused a Russian fighter jet of shooting down one of its spy planes over Abkhazia. Moscow denied involvement and said the flights broke UN regulations.

Abkhaz rebels declared Thursday that they had shot down another Georgian drone over the region. (dpa)