POTI, Georgia, (Reuters) – Russian forces manned a checkpoint on the road into Georgia’s main Black Sea port on Saturday, signalling the Kremlin’s intention to keep a tight grip on Georgia’s heartland despite Western criticism.

Georgian forces were once again controlling the country’s biggest East-West highway, and a Reuters cameraman saw a large column of Russian tanks and armoured cars leave a town near the Black Sea — evidence of Russia’s promised pullback. But the focus was shifting to the buffer zones stretching deep inside Georgia where Russia has said its troops will now maintain a permanent presence.

The Kremlin says it must stay on to prevent further bloodshed, but Georgia and its Western allies says the zones will give Russia a stranglehold over a country that lies on a transit route for energy exports from the Caspian Sea. “My view is that (the buffer zones) are against the spirit of the ceasefire agreement,” Alexander Stubb, Finland’s foreign minister and chairman of the Organisation for Security and Cooperation in Europe, told a Finnish broadcaster.

A Reuters reporter in Poti, Georgia’s main Black Sea port, said he could see 20 soldiers at a Russian checkpoint at the entrance to the town, 100 metres (yards) back from the road.

Up to 1,000 people gathered to protest against the Russian presence. “Why do they want to take control of Poti? They do not have such a right,” said 60-year-old Roland Silagava. “Maybe they want to grab Poti from us. While we are still alive we will not allow them to stay here. If they were our friends they would not do this.”

The conflict between Russia and pro-Western Georgia has left the United States, NATO and European Union groping for a response. Beyond freezing NATO’s contacts with Russia, the West looks to have little influence over energy powerhouse Russia.

Georgia’s busiest port for oil and oil products is to the south in Batumi, but Poti can load up to 100,000 barrels per day of oil products, which arrive by rail from Azerbaijan. Poti is also a major gateway for merchandise bound not only for Georgia but for other Caucasus republics and Central Asia.

In Moscow, a senior defence official said Russian troops would patrol Poti, even though it lies just outside the “zone of responsibility” Russia says is covered by its peacekeeping mandate in Georgia.

Anatoly Nogovitsyn, deputy chief of the Russian military’s General Staff, told reporters those patrols were in line with a ceasefire deal brokered by French President Nicolas Sarkozy. “Should we sit behind the fence? What use would we be then? They (Georgian forces) will drive around in Hummers, move munitions around in trucks, and are we supposed to just count them?” he said after a news briefing. He said he had reports the Georgian military, crushed in the week-long war with Russia, was re-arming and planning special forces operations.

Hundreds were killed and tens of thousands displaced in the fighting that erupted on Aug. 7-8. Moscow sent in troops after Georgia tried to retake its separatist South Ossetia region.

Russia defeated the assault and pushed on further, crossing the main East-West highway and moving close to a Western-backed oil pipeline. They also moved into Western Georgia from Abkhazia, a second breakaway region on the Black Sea.

Across Georgia on Saturday, Russian troops were pulling back but they left pockets of men and weapons inside the buffer zones which, observers say, could become the focus for a new confrontation.

A Reuters reporter saw Russian soldiers at a checkpoint in the village of Karaleti, six km (four miles) north of the central Georgian town of Gori and in territory where Tbilisi says Moscow has no right to station troops.

But for the first time since Russian troops moved in, Georgian forces were back in control of the main highway linking the capital Tbilisi to the Black Sea.

In Gori the grocery market re-opened for the first time since the fighting broke out. In Senaki, near the Black Sea, a Reuters cameraman saw a convoy of 150 Russian tanks, armoured vehicles and trucks pull back into rebel-held territory.

Inside South Ossetia, another Reuters reporter said he saw a dozen heavy howitzer guns, 50 armoured personnel carriers and 100 heavy trucks head back into Russia. The Russian driver of one truck was waving a captured Georgian flag.

The Russian military presence is a challenge to the growing U.S. influence in the region — a major overland trade route between Europe and Asia and a transit corridor for oil and gas exports from the Caspian Sea that is favoured by the West because it bypasses Russia.

Russia has denied any plans to annex Georgian territory, saying it only wants to protect South Ossetia and Abkhazia from a pro-Western Georgian leadership it accuses of dangerous aggression.

Most people in the two rebel regions hold Russian passports and do not want to be part of Georgia.