Security forces in Batumi, the capital of the rebel Georgian province of Ajaria, have broken up a protest against local leader Aslan Abashidze.
Dozens are said to have been injured in the protest by students and teachers
Dozens are said to have been injured in the protest by students and teachers, amid mounting tensions between Mr Abashidze and Georgia's president.
Mikhail Saakashvili has given Mr Abashidze until next week to disarm his militias and submit to Tbilisi's rule.
But Mr Abashidze has said the stand-off is heading toward conflict.
"Unless Georgian President (Mikhail Saakashvili) heeds
recommendations on avoiding bloodshed voiced by the European Union,
the United States and our neighbour Russia, another conflict zone
will appear on the world map," Mr Abashidze said in comments broadcast
overnight on local television.
Turkey, which borders Ajaria, is the latest country to express concern over the situation.
"Turkey is sure that the parties involved will act with cool
heads and caution so that current events do not move in an undesired
direction," the Turkish foreign ministry said in a statement.
State of emergency
Security forces in Batumi are said to have used water-cannon, batons and iron bars to break up the protest by students and teachers.
The independent Georgian television network Mze showed footage of uniformed men beating protesters, and of an unconscious woman.
The BBC's Natalia Antelava, in Batumi, says the protest was sparked, in part, by Mr Abashidze's decision to close schools and universities as part of a state of emergency in Ajaria.
Our correspondent notes their other demands were identical to Mr Saakashvili's - that Mr Abashidze disarm his paramilitary force, lift the state of emergency and restore road links with the rest of Georgia.
Mr Saakashvili has been locking horns with Mr Abashidze since he swept to power in last year's "rose revolution".
Georgia's president has promised to end corruption and remove figures
such as Mr Abashidze, who have held office since Soviet times.
'A real dictator'
The latest crisis flared after Mr Abashidze's forces blew up the three main bridges linking it to the rest of Georgia, and dismantled railway lines.
Mr Abashidze said he feared Georgian soldiers on exercises nearby were about to invade.
Georgia has rejected Mr Abashidze's allegations that it
intends to use force to bring Ajaria under control.
The region is now in a self-imposed blockade and local people report food prices are rising as people stock up on staples.
"He is a real dictator, a real dictator. What is he going to do? Starve us to death?" said one Batumi resident.
The opposition members say their offices and homes are being raided and that several of their activists have been detained.
The BBC's Chloe Arnold in Tbilisi says there is growing concern in the West about the situation.
Construction has begun on a multi-billion dollar pipeline to transport Caspian Sea oil through the volatile region to the international market.
The project is strongly backed by the US.
The US State Department has said it is "deeply concerned" about Mr Abashidze's actions.
On Monday the 45-country Council of Europe - the continent's main human rights body - urged both sides to ease tensions.
Russia has military bases in Ajaria, which are a source of tension between Georgia and Russia.