Beijing  - US President George W Bush on Monday said he had taken a "very firm" line with Russian leaders over the "unacceptable" violence in Georgia.

"I said this violence is unacceptable - I not only said it to (Russian Prime Minister) Vladimir Putin, I've said it to the president of the country, Dmitry Medvedev," Bush told US broadcaster NBC when asked about the conflict.

Bush said his government was trying to broker a cease-fire and a return to the military status quo of August 6.

"And, look, I expressed my grave concern about the disproportionate response of Russia and that we strongly condemn bombing outside of South Ossetia," he told NBC in an interview in Beijing.

"And I was very firm with Vladimir Putin... just like I was firm with the Russian president," he said after meeting the two leaders in Beijing over the weekend.

"There needs to be a international mediation there for the South Ossetia issue," Bush said.

The first Western mediators in Tiblisi to work for an end to the conflict between Georgia and Russia late Sunday called for an immediate ceasefire by all parties.

French Foreign Minister Bernard Kouchner, whose nation hold the rotating EU presidency, and Finnish Foreign Minister Alexander Stubb, head of the Organisation for Security and Cooperation in Europe (OSCE), met with Georgian President Mikheil Saakashvili.

Earlier Sunday, after nearly four days of fighting between Georgian and Russian troops in the breakaway region of South Ossetia Russian troops were in control of the capital Tskhinvali, as the Georgian government announced a unilateral ceasefire.

There were ongoing reports of continued fighting overnight, including the Russian bombing of the Georgian city of Gori and Georgian artillery fire in Tskhinvali. The reports could not be independently verified.

Bush said on Saturday that his country would work with partners in Europe to mediate a solution to the conflict.

On Friday, the United States announced that it was sending an envoy to help bring about a ceasefire in the conflict in Georgia's breakaway South Ossetia region. (dpa)