Georgian forces and South Ossetian separatists have been exchanging heavy fire just hours after agreeing to a ceasefire and Russian-mediated talks.
Georgian forces and South Ossetian separatists have been exchanging heavy fire just hours after agreeing to a ceasefire and Russian-mediated talks.
The BBC's Matthew Collin in Tbilisi says the separatist stronghold of Tskhinvali appears to be under siege, with a series of huge explosions.
Russian media reports said Georgia had launched a tank-led attack on the separatist stronghold of Tskhinvali, with at least 15 killed in shelling.
Georgia says an operation is under way to restore constitutional order.
Georgia says its aim is to finish "a criminal regime" and restore order.
But the Russian-backed separatists have appealed to Moscow and the world to protect them "extermination".
Moscow has called on the international community to jointly work "to avert massive bloodshed and new victims".
Russia has called on the international community to jointly work to "to avert massive bloodshed and new victims".
At Russia's request, members of the UN Security Council are to hold a rare emergency session shortly to discuss a response to the escalating violence.
At Moscow's request, members of the UN Security Council are expected to hold a rare emergency session shortly to discuss a response to the escalating violence.
The BBC's Matthew Collin in Tbilisi says there has been a series of huge explosions and rocket fire in and around Tskhinvali.
Hundreds of fighters from Russia and Georgia's other breakaway region of Abkhazia were heading to aid the separatist troops, Russian news agencies reported.
Hundreds of fighters from Russia and Georgia's other breakaway region of Abkhazia are reportedly heading to aid the separatist troops.
Meanwhile, the head of Georgian peacekeepers in South Ossetia said they were going to "restore constitutional order" to the region.
The Georgian minister for integration, Temur Yakobashvili, said Georgia's aim was not to take over the territory but to finish "a criminal regime".
'Perfidious step'
'Perfidious step'
South Ossetian rebel leader Eduard Kokoity told Russia's Interfax news agency that Georgia had launched an all-out attack on the town of Tskhinvali, in what he called "a perfidious and base step".
South Ossetian rebel leader Eduard Kokoity told Russia's Interfax news agency that Georgia had launched an all-out attack on the town of Tskhinvali, in what he called "a perfidious and base step".
Up to 10 Georgian soldiers died in Thursday's clashes, the Georgian interior ministry told AFP news agency.
The head of Georgian peacekeepers in South Ossetia said the operation was intended to "restore constitutional order" to the region.
Separatist authorities claimed on their website two civilians had been killed after coming under Georgian attack.
The Georgian Minister for Integration, Temur Yakobashvili, said Georgia's aim was not to take over the territory but to finish "a criminal regime".
Days of fierce conflict have raised fears of a new war in the volatile Caucasus.
Days of fierce conflict have raised fears of a new war in the volatile Caucasus.
In a televised address, Georgian President Mikhail Saakashvili earlier called for the bloodshed to end, but also warned the separatists not to try Tbilisi's patience.
In a televised address, Georgian President Mikhail Saakashvili earlier called for the bloodshed to end, but also warned the Russian-backed separatists not to try Tbilisi's patience.
A truce was later announced, with emergency talks set for Friday, but by nightfall, both sides were trading heavy fire.
A truce was later announced, with emergency talks set for Friday, but by nightfall, both sides were trading heavy fire.
Georgia accuses Russia of arming the South Ossetian authorities - who have been trying to break away since the civil war in the 1990s. Moscow denies the claim.
Georgia accuses Russia of arming the South Ossetian authorities - who have been trying to break away since the civil war in the 1990s. Moscow denies the claim.
President Saakashvili has vowed to restore Tbilisi's control over South Ossetia and Abkhazia.
President Saakashvili has vowed to restore Tbilisi's control over South Ossetia and Abkhazia.
The Ossetians have traditionally had good relations with Russia, and North Ossetia is part of the Russian Federation.
The Ossetians have traditionally had good relations with Russia, and North Ossetia is part of the Russian Federation.
Russia is hostile to Georgia's ambition to join Nato and has accused Georgia of building up its forces around the breakaway regions, where Russian peacekeeping troops are deployed.
Russia is hostile to Georgia's ambition to join Nato and has accused Georgia of building up its forces around the breakaway regions, where Russian peacekeeping troops are deployed.
Are you in South Ossetia or elsewhere in Georgia? Have you been caught up in events? Send us your comments using the form below:
Are you in South Ossetia or elsewhere in Georgia? Have you been caught up in events? Send us your comments using the form below:
