Russia expanded its bombing blitz Sunday against neighboring U.S.-allied Georgia, targeting the country's capital for the first time as Russian and Georgian troops continued battling for the contested province of South Ossetia.

Russian jets raided a plant on the eastern outskirts of Tbilisi that builds Su-25 ground jets used by Georgia in the conflict. The attack inflicted some damage to its runways but caused no casualties, said Georgia's Interior Ministry spokesman Shota Utiashvili.

"We heard a plane go over and then a big explosion," said Malkhaz Chachanidze, a 41-year old ceramics artist whose house is located just outside the fence of the factory, which has been running since the Soviet era. "It woke us up, everything shook."

Russian jets have been roaming Georgia's skies since Friday. They raided several air bases and bombed the Black Sea port city of Poti, which has a sizable oil shipment facility.

The Russian warplanes also struck near the Baku-Tbilisi-Ceyhan oil pipeline which carries Caspian crude to the West, but no supply interruptions have been reported.

U.S. President George W. Bush called for an end to the Russian bombings and an immediate halt to the violence.

"The attacks are occurring in regions of Georgia far from the zone of conflict in South Ossetia. They mark a dangerous escalation in the crisis," Bush said in a statement to reporters while attending the Olympic Games in Beijing.

Georgia President Mikhail Saakashvili called it an "unprovoked brutal Russian invasion."

A Russian raid on Gori near South Ossetia Saturday which apparently targeted a military base on the town's outskirts left numerous civilian casualties.

An Associated Press reporter who visited the town shortly after the strike saw several apartment buildings in ruins, some still on fire, and scores of dead bodies and bloodied civilians. The elderly, women and children were among the victims.

Russian officials said they weren't targeting civilians, but Russia's Foreign Minister Sergey Lavrov said that Georgia brought the airstrikes upon itself by bombing civilians and Russian peacekeepers in South Ossetia. He warned that the small Caucasus country should expect more attacks.

"Whatever side is used to bomb civilians and the positions of peacekeepers, this side is not safe and they should know this," Lavrov said.

Saakashvili on Saturday proposed a cease-fire, but Russia said it wants Georgia to first pull its troops from South Ossetia and sign a pledge not to use force against the breakaway province.

The diplomatic standoff continued Saturday in the U.N. Security Council, which met for the third time since late Thursday night to try to help resolve the situation. Another meeting requested by Georgia was scheduled for Sunday afternoon.

U.N. Secretary-General Ban Ki-moon urged "all parties to immediately end hostilities and to engage, without delay, in negotiations to achieve a peaceful settlement," his office said in a statement late Saturday.

Georgia, a U.S. ally whose troops have been trained by American soldiers, launched the major offensive to regain control over South Ossetia overnight Friday. Heavy rocket and artillery fire and air strikes pounded the provincial capital, Tskhinvali.

Lavrov told reporters Saturday that some 1,500 people had been killed in South Ossetia since Friday, with the death toll rising. The figures could not be independently confirmed.

But Tskhinvali residents who survived the bombardment by hiding in basements and later fled the city estimated that hundreds of civilians had died. They said bodies were lying everywhere.

Utiashvili, the Georgian Interior Ministry spokesman, said the Georgian troops were still in control of Tskhinvali on Sunday morning but added that Russian troops were attacking the city from several directions.

A Russian general said Saturday that his troops had driven the Georgian troops out of the city, but another Russian officer, Maj. Gen. Marat Kulakhmetov, admitted in televised remarks Sunday that the fighting in the city was continuing.

Alexander Lomaia, secretary of Georgia's Security Council, estimated that Russia sent 2,500 troops into Georgia. The Russian military would not comment on the number of troops.

In Saturday's meeting with refugees in the city of Vladikavkaz across the border, Prime Minister Vladimir Putin described Georgia's actions as "complete genocide. Putin also said Georgia had effectively lost the right to rule the breakaway province _ an indication Moscow could be preparing to fulfill South Ossetians' wish to be absorbed into Russia.

The risk of the conflict setting off a wider war also increased when Russian-supported separatists in another Georgia's breakaway region, Abkhazia, launched air and artillery strikes on Georgian troops to drive them out of a small part of the province they control. The separatists told 15 U.N. military observers to evacuate.

Georgia's Foreign Ministry said the country was "in a state of war" and accused Russia of beginning a "massive military aggression." The Georgian parliament approved a state of martial law, mobilizing reservists and ordering government authorities to work round-the-clock.

Russia's President Dmitry Medvedev said that Moscow sent troops into South Ossetia to protect its peacekeepers and civilians on a mission to "enforce peace." He said that Russia would seek to bring the Georgian attackers to criminal responsibility.

Medvedev said he was ordering the military prosecutor to document crimes against civilians in South Ossetia.

Georgia borders the Black Sea between Turkey and Russia and was ruled by Moscow for most of the two centuries preceding the breakup of the Soviet Union. Today, Russia has approximately 30 times more people than Georgia and 240 times the area.

Both South Ossetia and Abkhazia have run their own affairs without international recognition since splitting from Georgia in the early 1990s and have built up ties with Moscow. Russia has granted its passports to most of their residents.

Russia also laid much of the responsibility for ending the fighting on Washington, which has trained Georgian troops. Washington, in turned, blamed Russia.

White House spokesman Gordon Johndroe said Bush had spoken with both Medvedev and Saakashvili. But it was unclear what might persuade either side to stop shooting _ both claim the other violated a cease-fire declared Thursday.

Georgia said it has shot down 10 Russian planes, including four brought down Saturday, according to Lomaia. It also claimed to have captured two Russian pilots, who were shown on Georgian television.

Russian Col. Gen. Anatoly Nogovitsyn, deputy chief of the General Staff, confirmed Saturday that two Russian planes had been shot down, but did not say where or when.

Russian military commanders said 15 peacekeepers have been killed and about 150 wounded in South Ossetia, accusing Georgian troops of killing and wounding Russian peacekeepers when they seized Russian checkpoints. The allegations couldn't be independently confirmed.

Russia's Vesti 24 television reported that its crew of three were wounded in a Georgian shelling of a Russian military convoy near Tskhinvali which also left a Russian general wounded.

In Abkhazia, the separatist government said it intended to push Georgian forces out of the Kodori Gorge. The northern part of the gorge is the only area of Abkhazia that has remained under Georgian government control.

Lomaia, the Georgian security chief, said that Georgian administrative buildings and two villages in the Kodori Gorge were bombed, but he blamed the attack on Russia. He said there were no casualties.

Lomaia said that Russians also raided a Georgian military faciliy in the Zugdidi region just south of Abkhazia, inflicting no casualties.

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Associated Press writers Misha Dzhindzhikhashvili in Tbilisi, Georgia; Douglas Birch on the Russian-Georgian border; George Abdaladze in Gori, Georgia; and Jim Heintz, Vladimir Isachenkov and Lynn Berry in Moscow contributed to this report.