Germany has called on Russia to honour a ceasefire agreement it signed last weekend and pull its troops back to positions held in Georgia before the outbreak of hostilities in that country.

The ceasefire allows Russia to maintain troops in a zone extending about six kilometres into Georgia along the South Ossetian border.

Russian soldiers guard their new military position at the entrance of the Black Sea port city of Poti in western Georgia on Saturday. (Bela Szandelszky/Associated Press)

However, journalists say Russian soldiers have been digging new positions around the city of Poti, which lies well outside the security zone where Russian peacekeeping forces are allowed to stay on Georgian soil.

"The [German] government expects Russia to complete the withdrawal immediately in accordance with the six-point plan also signed by Russian President Dmitry Medvedev, and pull back its troops to the lines held before the outbreak of hostilities, as was agreed," spokesman Thomas Steg said in a statement on Saturday.

"According to our information, Russia has begun its withdrawal from Georgia, but not completed it," Steg added.

Russia sent tanks and thousands of troops into Georgia two weeks ago, after Georgia launched a surprise military operation to force the breakaway province of South Ossetia back under central control.

Russian troops first travelled into South Ossetia, then pushed south beyond its borders into the city of Gori and took control of the main east-west highway leading to the capital, Tbilisi.

Even after signing the French-brokered ceasefire agreement, Russian troops blew up a railway bridge that spans the Kvari river, about 40 kilometres west of Tbilisi, cutting a vital transport link from two Black Sea ports to the Georgian capital.

Moscow said it was forced to intercede for the sake of citizens in the region. Most residents of the separatist province carry Russian passports.

On Friday, Russians military vehicles stationed in Gori, where hundreds were killed in the fighting and tens of thousands were forced to flee, left the city and headed north into South Ossetia.

Russian troops also left Georgia's western Senaki military base and the eastern checkpoint of Igoeti, 50 kilometres from Tbilisi.

However, Russian troops and armoured personnel carriers stayed in positions near Senaki and the Black Sea port city of Poti, raising questions about Russia's intentions.

Russia has defended plans to keep its forces in Poti, saying it does not break terms of the ceasefire deal.

It's not clear how long Moscow will keep tanks and troops at a new checkpoint not far from Gori or another Russian-proclaimed security zone near Abkhazia, a second separatist region in Georgia with close ties to Russia.