* Moscow says several Russian peacekeepers killed
* Georgia says Russian planes drop bombs
* EU and White House urge end to violence
MEGVREKISI, Georgia, Aug 8 (Reuters) - Fighting raged in and around the capital of Georgia's breakaway South Ossetia region on Friday as Georgian troops, backed by warplanes, pounded separatist forces in a bid to re-take control of the territory.
A Reuters correspondent said the roar of warplanes and the explosions of heavy shells were deafening more than three km (two miles) from the town. Many houses were ablaze.
Georgia's pro-Western president, Mikheil Saakashvili, said his forces had "freed" the greater part of the territory's capital, Tskhinvali, and ordered a full-scale mobilisation of military reservists.
Georgia said four Russian jets entered Georgian airspace and dropped bombs on two places just south of the territory, which has been outside central government control since the 1990s.
There was no immediate comment on the report from Moscow.
The crisis, the first to confront Russian President Dmitry Medvedev since he took office in May, has fuelled fears of full-blown war in a region emerging as a key energy transit route and where Russia and the West are vying for influence.
The European Union and the United States, a vocal Georgian ally, urged a halt to the bloodshed while Moscow vowed to respond after it said several Russian peacekeepers were killed by Georgian artillery fire.
"Some shells directly hit (their) barracks in Tskhinvali," the breakaway capital, Russia's Interfax news agency quoted a peacekeepers' spokesman as saying.
Andrei Chistyakov, a correspondent for Russia's Vesti-24 television station, said at least 15 civilians had been killed in Tskhinvali, where thousands of people took refuge in cellars.
"These are the people whose bodies were seen in their yards and in the streets," he said by telephone.
Georgia said its operation, launched after a week of clashes between separatists and Georgian troops in which nearly 20 people were killed, was aimed at ending South Ossetia's effective independence, won in a 1991-92 war.
Russian Prime Minister Vladimir Putin, visiting Beijing, said Georgia had used heavy armour and artillery.
"The Georgian leadership has resorted to very aggressive actions, he said. "There are casualties, including among Russian peacekeepers. This is very sad and this will incur a response."
EMERGENCY U.N. SESSION
Georgian Interior Ministry spokesman Shota Utiashvili said government forces had fought mercenaries who had entered South Ossetia from Russia.
Georgian Prime Minister Lado Gurgenidze said the operation would continue until a "durable peace" had been reached.
The government and separatist envoys had been due to meet in Tskhinvali for Russian-mediated peace talks on Friday.
The Kremlin said Medvedev had summoned his top security advisers to discuss how to restore peace and defend civilians "within the peacekeeping mandate we have".
At an emergency session of the United Nations on Thursday night, Russia failed to push through a statement that would have called on both sides to stop fighting immediately.
Council diplomats said a phrase calling on all sides to "renounce the use of force" had been unacceptable to the Georgians, backed by the United States and the Europeans.
Georgian leader Saakashvili, who wants to take his small Caucasus nation into NATO, has made it a priority to win back control of South Ossetia and Abkhazia, another rebel region on the Black Sea.
The issue has bedevilled Georgia's relations with Russia, which is angered by Tbilisi's moves towards the Western fold and its pursuit of NATO membership.
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