The standoff took on an international dimension as neighbouring Russia sided with Adjara's leader Aslan Abashidze, after Georgia's President Mikhail Saakashvili was barred from entering the coastal territory.

Saakashvili tried to cross into Adjara near the town of Choloki, but was met by tanks and armed men loyal to Abashidze. He turned back after automatic weapons were fired into the air in warning, saying he did not want to provoke bloodshed.

In Moscow, Abashidze later reported speaking to Saakashvili, but accused the Georgian leader of threatening him in the phone call to "shoot down my plane" should he try to return to Adjara.

Tensions between Abashidze and Saakashvili -- the newly elected leader of the tumultuous Caucasus republic -- have been simmering for weeks, but it has now sparked renewed concern in the West.

The Council of Europe's Walter Schwimmer expressed "alarm over the escalation of tensions between Tbilisi and Batumi."

Moscow had earlier warned Tbilisi it would be held responsible if the situation turned violent, while inside Adjara there were reports that local authorities had mobilised tanks and were arming local people in anticipation of an attack by Georgian government forces.

According to the latest reports from the scene, Saakashvili had returned to the checkpoint on the border with Adjara with an armed escort and addressed the 1,000-strong crowd assembled there.

"The president must have the ability to move about freely," he said, speaking through a megaphone.

"I guarantee that we will observe all safety measures when it comes to the civilian population. We will do everything in our power to solve this problem in a peaceful manner."

Vano Merabishvili, head of Georgia's Security Council, said in televised comments that Abashidze's administration had mobilised tanks on the streets of the regional capital, Batumi, and was handing out weapons to local people.

Georgia's government responded Sunday by placing its military on high alert, and by closing Adjara's airspace to any non-military flights.

This was seen as an attempt to prevent Abashidze, who is currently in Moscow garnering support from the Russian authorities, from returning to Adjara.

"As a result of the situation in Adjara, armed forces have been put on a heightened state of alert," Givi Yukuridze, head of Georgia's Joint Chiefs of Staff, told AFP by telephone.

The situation was made all the more explosive because Russia has a military base in Adjara, a hangover from Soviet rule, and there were fears these troops could be mobilised on the side of the Adjaran authorities.

Speaking earlier Sunday, Saakashvili warned in televised comments that "not a single tank can leave the territory of the base. Any movement of Russia's military equipment could provoke bloodshed."

Russia is a traditional ally of Abashidze, and the Kremlin issued Saakashvili with a stern warning not to use force to try to bring the renegade leader into line.

"There is reliable information that (Georgia's capital) Tbilisi is planning to use force," Russian foreign ministry spokesman Alexander Yakovenko was quoted as saying by Interfax news agency.

"Georgia's authorities must realise that such provocative actions can lead to the most grave and unpredictable consequences, most of all for Georgia itself."

"Should there be a crisis, the full brunt of responsibility will lie with Georgia's leadership," the spokesman added.

Relations between Tbilisi and Adjara have been tense for years. Abashidze runs the region like a personal fiefdom, has withheld taxes from the central government and has set up a powerful local militia which takes orders only from him.

Since its independence, Georgia has been riven by separatism. Two regions, Abkhazia and South Ossetia, refuse to accept Tbilisi's sovereignty over them. But Saakashvili has vowed that Adjara will not be allowed to follow the same path.

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