Russian troops in Georgia's breakaway region of South Ossetia are carrying out a peace enforcement operation aimed at protecting civilians, President Dmitry Medvedev said on Saturday.

"Our peacekeepeers and reinforcement units are currently running an operation to force the Georgian side to (agree to) peace," Russian news agencies quoted Medvedev as saying at a meeting with Defence Minister Anatoly Serdyukov.

"They are also responsible for protecting the population. That's what we are doing now," Medvedev added. Chief of General Staff Nikolai Makarov was also present at the meeting called to update the president on the situation.

Russian troops poured into South Ossetia on Friday, hours after Georgia launched a large-scale offensive aimed at restoring control over the province lost after a war in the early 1990s.

Russia is the main backer of South Ossetian separatists and the majority of the population, who are ethnically different from Georgians, have been given Russian passports.

Tbilisi accuses Russia of launching a war against it.

Russia sent fresh reinforcements overnight, which according to Russian news agencies have reached the regional capital Tskhinvali where fierce battles rage. The Russian military said more reinforcements were on their way.