Explosions can be heard near the Georgian city of Gori as a Russian troop withdrawal appears to be in collapse, Fox News reported.
The Georgian Foreign Ministry says more Russian troops have moved into the city of Gori after a withdrawal had appeared to be under way earlier in the day.
Ministry spokeswoman Nato Chikovani said Thursday that Russian troops also moved into the Black Sea oil port city of Poti, from which they had appeared to leave earlier.
"Just a few minutes ago they (Russians) entered Poti in tanks," a shipping agent told Reuters by telephone. "Some of the guys have blue signs, badges, which means they should be peacekeepers."
Russian and Georgian soldiers briefly confronted each other at a checkpoint on the outskirts of Gori around midday. Russian tanks hurried to the scene to force the Georgians to back off.
The cause of the apparent breakdown of the Russians' withdrawal from Gori was not immediately known, although some Georgian police said the Russian's South Ossetian allies had refused to leave the city.
Russia's foreign minister says the question of Georgia's territorial integrity is a dead issue, a clear sign that Moscow is giving full backing to two separate regions in the wake of recent fighting and could absorb them.
Foreign Minister Sergey Lavrov made the statement Thursday simultaneously with the announcement that Russian President Dmitry Medvedev was meeting in the Kremlin with the separatist regions' leaders.
"One can forget about any talk about Georgia's territorial integrity because, I believe, it is impossible to persuade South Ossetia and Abkhazia to agree with the logic that they can be forced back into the Georgian state," Lavrov told reporters.
The United States meanwhile began sending in humanitarian aid, the first tangible results of an American response that Georgia's leader suggests has been confused and naive. The first shipment arrived on a huge military C-17, a veiled reminder of the close U.S.-Georgia military cooperation that has angered Russia.
Ministry spokesman Shota Utiashvili said that Russian troops, have also left Poti, a Black Sea port city with an oil terminal that is key to Georgia's fragile economic health.
Georgian police on the outskirts of Gori were halting civilian traffic on Thursday morning, and scores of light vehicles carrying Georgian soldiers were parked in the area. The soldiers said they were awaiting further orders.