Russian President Dmitry Medvedev described the situation in Georgia's embattled breakaway region of South Ossetia as a "humanitarian catastrophe," Reuters reported Russian news agencies as saying Saturday.
"People who are responsible for this humanitarian catastrophe should carry responsibility for what they have done," they quoted Medvedev as telling officials summoned to discuss humanitarian aid to the province. "Our task is to help overcome the consequences of the humanitarian catastrophe."
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Russia sent hundreds of troops to the Georgian separatist region of South Ossetia and threatened new air attacks on Georgian military bases Saturday as fighting raged for a second day.
Russian military aircraft also raided a Georgian town, leaving scores of civilians killed or wounded.
An Associated Press reporter who visited the town of Gori shortly after the Russian raid Saturday saw several apartment buildings ravaged by the Russian strike and scores of dead bodies and bloodied civilians, including elderly people, women and children.
The Russian planes appeared to target a military base on the outskirts of Gori which sustained hits, but they also struck living quarters nearby.
Georgia, a staunch U.S. ally, launched a major offensive Friday to retake control over South Ossetia. Russia, which has close ties to the region and has peacekeepers there, responded by sending in armed convoys.
About 1,500 people have been killed and the death toll continued to rise, Russian Foreign Minister Sergey Lavrov told journalists Saturday. The figure could not be independently confirmed, but people who fled the fighting said hundreds of civilians had probably died.
Witnesses said that most of the provincial capital, Tskhinvali, was in ruins and bodies were everywhere. Television footage showed burned out Georgian tanks, and sporadic fighting continued overnight and into Saturday.
The fighting threatened to ignite a wider war between Georgia and Russia. It also seemed likely to increase tensions between Moscow and Washington, which Lavrov said should bear part of the blame for arming and training Georgian soldiers.
Georgia has accused Russia of bombing its towns, ports and air bases and has asked the international community to help end what it called Russian aggression.
Kakha Lomaya, the head of Georgia's Security Council, said Georgia has shot down 10 Russian planes, including four brought down Saturday.
The first Russian confirmation that any of its planes had been shot down came Saturday from Col. Gen. Anatoly Nogovitsyn, the deputy chief of the General Staff, who said two Russian planes were downed. He did not say where or when.
Russia has said it needs to act to protect its peacekeepers and civilians in South Ossetia, most of whom hold Russian passports. Medvedev said Saturday that the troops were sent in to force Georgia into a cease fire.
Georgia's Interior Ministry spokesman Shota Utiashvili said the Vaziani military base on the outskirts of the Georgian capital was bombed by Russian warplanes during the night and that bombs fell in the area of the Baku-Tbilisi-Ceyhan oil pipeline.
He also said two other Georgian military bases were hit and that warplanes bombed the Black Sea port city of Poti, which has a sizable oil shipment facility.
Utiashvili said there apparently were significant casualties and damage in the attacks, but that further details would not be known until the morning.
Asked to comment on the Georgian claims of Russian bombing, Lavrov said it was Georgia that had bombed Russian peacekeepers and civilians and warned that the small Caucasus country should not feel safe.
"Whatever side is used to bomb civilians and the positions of peacekeepers, this side is not safe and they should know this," he said.
Asked whether Russia could bomb the Georgian capital, Tbilisi, he answered: "I don't think the bombing is coming from Tbilisi, but whatever part of Georgia is used for this aggression is not safe."
Diplomats have issued a flurry of statements calling on both sides to halt the fighting and called for another emergency session of the United Nations Security Council, its second since early Friday morning seeking to prevent an all-out war.
U.S. Secretary of State Condoleezza Rice urged Russia to halt aircraft and missile attacks and withdraw combat forces from Georgian territory. Rice said in a statement the United States wants Russia to respect Georgian sovereignty and agree to international mediation.
There were conflicting claims as to who held the battlefield advantage.
Georgia's President Mikhail Saakashvili said "Georgian military forces completely control all the territory of South Ossetia" except for a northern section adjacent to Russia.
Shota Utiashvili, spokesman for the Georgian Interior Ministry, said that Georgian forces remained in control of the provincial capital, fending off Russian attacks.
But Russian military spokesman Col. Igor Konashenkov said Russian armor and infantry were deployed on the outskirts of Tskhinvali and were prepared for what he described as a mission to "enforce peace."
Konashenkov said the Russian troops were ordered to "harshly suppress any shooting."
Eyewitnesses said that separatist and Russian forces seemed to be in control of Tskhinvali center with no Georgian troops visible there on Saturday morning. Horrified civilians crawled out of the basements into the streets as fighting eased, looking for supplies.
The air and artillery bombardment left the city without water, food, electricity and gas.
Konashenkov, who accused Georgian forces of deliberately attacking Russian peacekeepers with heavy weapons, said that 15 peacekeepers have been killed and about 70 wounded.
He alleged that Georgian troops had killed some wounded Russian peacekeepers when they seized Russian checkpoints. Konashenkov's claim couldn't be independently confirmed.
It was unclear what might persuade either side to stop shooting. Both claim the battle started after the other side violated a cease-fire that had been declared just hours earlier after a week of sporadic clashes.
The United States was sending in its top Caucasus envoy, Deputy Assistant Secretary of State Matthew Bryza, to try to end the bloodshed.
It was the worst outbreak of hostilities since the province won de facto independence in a war against Georgia that ended in 1992. Russian troops went in as peacekeepers but Georgia alleges they now back the separatists.
Russia, which has granted citizenship to most of the region's residents, appeared to lay much of the responsibility for ending the fighting on Washington.
Georgia, which borders the Black Sea between Turkey and Russia, was ruled by Moscow for most of the two centuries preceding the breakup of the Soviet Union. Georgia has angered Russia by seeking NATO membership — a bid Moscow regards as part of a Western effort to weaken its influence in the region.
Saakashvili, a U.S.-educated lawyer, long has pledged to restore Tbilisi's rule over South Ossetia and another breakaway province, Abkhazia. Both regions have run their own affairs without international recognition since splitting from Georgia in the early 1990s and have built up ties with Moscow.
Georgia has about 2,000 troops in Iraq, making it the third-largest contributor to coalition forces after the U.S. and Britain. But Saakashvili has called them home in the face of the South Ossetia fighting. The Georgian commander of the brigade in Iraq said Saturday they would leave as soon as transport can be arranged.
Associated Press writers Douglas Birch and Musa Sadulayev in Vladikavkaz and Vladimir Isachenkov and Lynn Berry in Moscow contributed to this report.