Moscow said it was handing over control of Gori, a key Georgian town 60 km (35 miles) east of the capital Tbilisi which lies near the main road connecting eastern and western Georgia. Russia had earlier denied having troops in the town.
"For another two days Russian troops will stay in the region to carry out procedures of handing over control functions to Georgian law enforcement bodies after which they will leave," Major-General Vyacheslav Borisov told Russian news agencies.
In the Black Sea port of Poti, a small oil terminal, witnesses said Russian tanks had rolled in on Thursday morning, accompanying trucks carrying troops to the port area. "Just a few minutes ago, they (Russians) entered Poti in tanks," shipping agent Nikoloz Gogoli told Reuters by telephone.
The harbourmaster in Poti, who did not want to give his name, said Russian troops sank six Georgian cutters -- old military boats -- based at Poti on Wednesday. Gogoli said the cutters were blown up with explosives and that Russian troops warned bystanders of their plans. Nobody was hurt, he added.
Russia's deputy chief of the General Staff, Colonel-General Anatoly Nogovitsyn, denied Moscow had armour or troops in Poti.
Stepping up diplomatic efforts to end the week-old conflict, U.S. Secretary of State Condoleezza Rice was to meet the architect of the European Union-sponsored ceasefire, French President Nicolas Sarkozy, before heading to Tbilisi.
The conflict has unnerved oil markets because of the region's importance as an energy transit route from the Caspian to Europe and alarmed Western governments because of its potential to spiral into a bigger international confrontation.
Sarkozy negotiated a six-point ceasefire which appears to have halted most of the combat, although there were reports from the conflict zone of marauding Ossetian militias burning and looting Georgian villages to exact revenge.
Human Rights Watch (HRW) activists said they saw looting on Wednesday though it appeared to be on a less intensive scale than on Tuesday, when they saw many houses burning in four villages inhabited by ethnic Georgians in South Ossetia.
"They were moving cattle and furniture. They were wearing combat fatigues," Tanya Lokshina of U.S.-based HRW said from the South Ossetian capital Tskhinvali on Thursday. "But on Wednesday the Russian military were trying to rein them in," she said.
Russian Foreign Minister Sergei Lavrov said Moscow's forces "have received strict orders from the supreme commander-in-chief to apply wartime laws to looters". South Ossetian authorities said they had shot dead two looters on Wednesday.
EU foreign ministers agreed in principle on Wednesday to send monitors to supervise the truce but said any wider European peacekeeping operation would need a U.N. resolution.
Georgia has repeatedly alleged that Russia is violating the ceasefire by moving forces into Georgian towns such as Gori and the Black Sea port of Poti. Moscow denies breaking the truce, saying a clause in the plan allows it to "implement additional security measures" while awaiting international monitors.
Russian forces said they had shot down a total of three Georgian spy drones over South Ossetia and reported sniper attacks by Georgian special forces on and around Tskhinvali.
U.S. President George Bush, flanked by Rice and Defence Secretary Robert Gates at the White House, demanded on Wednesday Moscow end the crisis, abide by the agreed ceasefire and withdraw its troops from Georgia.
"The United States of America stands with the democratically elected government of Georgia. We insist that the sovereignty and territorial integrity of Georgia be respected," Bush said.
Lavrov said on Wednesday Washington needed to choose between partnership with Moscow or the Georgian leadership, which he characterised as a "virtual project" of the Bush administration. Rice bristled when asked about Lavrov's comments.
"Georgia is a democratic government in the Caucasus that has elected leaders. To call it a project of any place, of anybody, perhaps belies more about what Russia thinks about its neighbours that what it thinks about U.S. policy," she said.
Bush, who spoke with Georgian President Mikheil Saakashvili earlier in the day, ordered humanitarian supplies to be delivered to Tbilisi on U.S. military aircraft. A U.S. C-17 military aircraft carrying supplies arrived in Georgia and a second flight was planned for Thursday.
Speaking in Tbilisi, Saakashvili said Bush's pledge meant Georgian ports and airports would be taken under U.S. military control -- a claim swiftly denied by the Pentagon. Russia says 1,600 civilians died when Georgia attacked South Ossetia.
The figure has not been independently verified and Human Rights Watch researchers have cast doubt on it. Moscow's General Staff says it lost 74 soldiers in the fighting, with 171 wounded and 19 missing.
Tbilisi puts deaths on its side at over 175, with hundreds injured. That figure does not include South Ossetia.