Washington  - US President George W Bush said Monday that Russia's assault in Georgia is a "dramatic and brutal escalation" that appears meant to topple the Georgian government.

"It now appears that an effort may be underway to depose (Georgia's) duly elected government," Bush said at the White House shortly after returning from the Olympics in Beijing.

Bush said there was evidence that Russia intends to bomb the civilian airport near the Georgian capital Tbilisi, as Moscow continues its attack on Georgian targets outside of South Ossetia, the breakaway province where the conflict erupted last week.

"I am deeply concerned by reports that Russian troops have moved beyond the zone of conflict," Bush said.

Bush said that Russia's military campaign has diminished its own global standing, and called on President Dmitry Medvedev and Prime Minister Vladimir Putin to immediately agree to a ceasefire.

"These actions have substantially damaged Russia's standing in the world," Bush said. (dpa)