A delegation of European and US envoys is heading to Georgia as its conflict with Russia over the breakaway South Ossetia region deepens.
The envoys hope to broker a truce after three days of fighting which are said to have killed or injured hundreds, and sent thousands fleeing.
Russian jets have bombed several towns, including Gori in central Georgia.
Russia says it wants Georgian forces to withdraw to the positions they held outside South Ossetia before Thursday.
In the absence of independent verification, there are conflicting figures about the casualties suffered on both sides but the numbers appeared to rise sharply on Saturday.
Air and ground attacks around South Ossetia on Saturday
Based on Russian and South Ossetian estimates, the death toll on the South Ossetian side was at least 1,400. According to Moscow, all but a few of the dead were civilians.
Georgian casualty figures ranged from 82 dead, including 37 civilians, to a figure of around 130 dead.
A Russian air strike on Gori, a Georgian town near South Ossetia, left 60 people dead, many of them civilians, Georgia says.
Based on information supplied by both sides, the UN refugee agency believes that about 2,400 people have fled South Ossetia to other parts of Georgia while between 4,000 and 5,000 have crossed the border into Russia.
It comes as a third emergency session of the UN Security Council ended without an agreement on the wording of a statement calling for a ceasefire. UK Foreign Secretary David Miliband said Britain would "lend its strong support to all those committed to a swift resolution to the conflict".
But emmissaries from the US and Europe who are Nato members may not be seen as honest brokers by the Kremlin, when it comes to Georgia, BBC's diplomatic correspondent Bridget Kendall says.
The danger now is that Russia will not only use this crisis to demonstrate its military power in the region, but argue it is time to redraw the map, she adds.
Russian PM Vladimir Putin arrived in Russia's North Ossetia region on his return from the Olympics on Saturday.
He described the violence as "genocide", Russian media report.
Earlier, Mr Putin said it was unlikely now that South Ossetia would reintegrate with the rest of Georgia.
Georgian President Mikhail Saakashvili denounces the Russian military action
This, our diplomatic correspondent says, is precisely the outcome Georgia was trying to avoid.
Russia's ambassador to Nato, Dmitry Rogozin, said there could be no "consultations" with Georgia until Georgian forces returned to their positions and re-established "the status quo".
The crisis began spiralling when Georgian forces launched a surprise attack on Thursday night to regain control of South Ossetia, which has had de facto independence since the end of a civil war in 1992.
The move followed days of exchanges of heavy fire with the Russian-backed separatists, led by Eduard Kokoity.
In response to the Georgian crackdown, Moscow sent armoured units across the border into South Ossetia.
Fighting continued around Tskhinvali overnight and into Saturday morning, although not at the same intensity as on Friday, Russian media reported.
SOUTH OSSETIA TIMELINE
1991-92 S Ossetia fights war to break away from newly independent Georgia; Russia enforces truce
2004 Mikhail Saakashvili elected Georgian president, promising to recover lost territories
2006 S Ossetians vote for independence in unofficial referendum
April 2008 Russia steps up ties with Abkhazia and South Ossetia
July 2008 Russia admits flying jets over S Ossetia; Russia and Georgia accuse each other of military build-up
7 August 2008 After escalating Georgian-Ossetian clashes, sides agree to ceasefire; however Georgia launches a surprise attack
8 August 2008 Russia sends in columns of armour and troops and fighting erupts with Georgian forces in and around Tskhinvali
9 August 2008 Russian jets bomb central Georgian town of Gori, Russia says its troops have "liberated" Tskhinvali
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