Georgian soldiers sit atop a tank as it moves along a street in Gori, Georgia, just outside the breakaway province of South Ossetia on Monday. (Sergei Grits/Associated Press)

Russian troops on Monday invaded parts of western Georgia and launched new raids across the country as fighting raged in the breakaway Georgian province of South Ossetia.

Georgia's president said his country has been effectively cut in half with the capture of the central city of Gori, located on the country's main east-west highway about 100 kilometres from the capital, Tbilisi.

"[Russian forces] came to the central route and cut off connections between western and eastern Georgia," President Mikhail Saakashvili told a meeting of Georgia's National Security Council.

An Associated Press reporter based in Gori reported Georgian soldiers were warning locals to get out because Russian tanks were approaching. Reuters new agency, however, said its witnesses in Gori reported no sign of any Russian soldiers.

Georgian Defence Ministry officials said Russian troops had also seized a military base in the town of Senaki, about 30 kilometres inland from the Black Sea. A Georgian Interior Ministry spokesman said Russian forces also took over police stations in the town of Zugdidi, which is about 30 kilometres from Senaki.

In Moscow, a government official, who spoke to the Associated Press on condition of anonymity because he wasn't authorized to give his name, said the move into Senaki was intended to end Georgian resistance.

Meanwhile, fighting continued Monday around Tskhinvali, the capital of the separatist Georgian province South Ossetia, which has been devastated by heavy shelling and air strikes.

The United Nations called an emergency session at Georgia's request.

Russian troops on Monday invaded locations in western Georgia. (CBC)

Seven of the members of the G8 group of nations — Canada, the United States, Britain, France, Germany, Italy and Japan — called on Russia, the other member, to accept an immediate ceasefire.

Prime Minister Stephen Harper released a statement Monday condemning Russia’s incursions into Georgian territory beyond South Ossetia, including into Abkhazia, another breakaway province, from which Russia reportedly launched its invasion into Georgia.

"In escalating the conflict through its attacks on Georgian towns and cities outside South Ossetia, Russia has ceased to act as a peacekeeper. It is imperative that Russia respects the sovereignty and territorial integrity of Georgia," the statement said.

U.S. President George W. Bush called on Russia to immediately withdraw its troops from the conflict zone, saying he had evidence suggesting that Russian forces may soon begin bombing the civilian airport in the Georgian capital, Tbilisi.

Warning of a "dramatic and brutal escalation" of Russian force in the former Soviet republic, Bush said in a statement that there appeared to be an attempt by Russia to unseat Georgia's pro-Western president, Mikhail Saakashvili.

"I just met with my national security team to discuss the situation in Georgia. I am deeply concerned by reports that Russian troops have moved beyond the zone of conflict, attacked the Georgian town of Gori and are threatening the Georgian capital, Tbilisi," Bush said.

If the reports are accurate, Bush said the actions "would be inconsistent with assurances that we have received from Russia that its objectives were limited" to restoring peace in separatist pro-Russian areas.

Dispute over death count

The violence began late last week after Georgia launched a major military offensive against South Ossetia to regain the region, following alleged attacks from separatist rebels. The Georgian breakaway territory claims Georgia violated a ceasefire.

Russia responded by sending troops into the region on Friday, and Russian officials said more than 2,000 people have been killed, most of them Ossetians with Russian passports. The figures could not be independently confirmed. Georgian officials said 300 civilians have died.

Georgia's Interior Ministry said Russian planes bombed a military base and radar installation near Tbilisi on Monday. However, the CBC's Mike Hornbrook, reporting from the capital, said Tbilisi did not appear to be under threat of invasion and that there were no blockades or soldiers in the streets.

Georgian leader signs ceasefire

Hornbrook said Saakashvili held a news conference Monday and appealed to the international community to come together and with one voice call on Russia to stop its attack on Georgia.

"Saakashvili says the Russians are bent on regime change. In very emotional language, he claimed the Russians were engaged in ethnic cleansing," Hornbrook said.

Russia made a similar accusation against Georgia on Monday, with its Deputy Prime Minister Sergei Ivanov telling CNN that the former Soviet republic was trying to eliminate the population of South Ossetia in order to reintegrate the province back into Georgia.

Earlier in the day, the Georgian president signed a document in the presence of the foreign minister of France and representatives from the European Union.

The document "confirmed Georgia was halting all military activities," Hornbrook said.

Nonetheless, Georgian forces reportedly continued to fire on their Russian adversaries throughout the day.

Russia's Interfax news agency quoted a Russian general as saying Georgian forces had directed heavy fire early Monday at positions around Tskhinvali.

"Active fighting has been going on in several zones," Interfax quoted Maj.-Gen. Marat Kulakhmetov as saying.

Russia also said it had sunk a Georgian boat that tried to attack Russian vessels in the Black Sea.

Putin speaks out

Also on Monday, Russian Prime Minister Vladimir Putin criticized Washington for flying home an estimated 2,000 Georgian troops who had been deployed to Iraq.

"It's a pity that some of our partners, instead of helping, are, in fact, trying to get in the way," Putin said at a cabinet meeting.

"I mean, among other things, the United States airlifting Georgia's military contingent from Iraq effectively into the conflict zone," he said.

In other developments:

• The European Union issued a statement urging an end to the violence. EU envoys were planning to travel to Moscow from Tbilisi to promote a ceasefire proposal.
• NATO Secretary General Jaap de Hoop Scheffer accused Russia of using disproportionate force and violating Georgia's territory.
• The United Nations said it was continuing to distribute emergency food aid to help thousands in Georgia, mostly near Tbilisi, who have been displaced by the fighting.
• In Brussels, demonstrators gathered outside the Russian mission to the European Union to protest Russia's actions in South Ossetia and Georgia.
• The presidents of Poland, Estonia, Latvia and Lithuania issued a joint statement denouncing the Russian action and called on NATO and the EU to stand up to Moscow.

With files from the Associated Press