Russian tanks have been seen leaving the Georgian city of Gori under a cease-fire agreement signed last week.

Journalists in the city witnessed the pullback Tuesday. Russian officers said the tanks were headed toward Georgia's breakaway region of South Ossetia and then would continue across the border into Russia.

It was unclear whether the action was a sign of the start of a full Russian military withdrawal from Georgia as required under the cease-fire.  Russian forces and military vehicles are still occupying large areas of the country, including the major Black Sea port of Poti. 

In Washington, Pentagon spokesman Bryan Whitman says the United States has yet to see any significant movement of Russian forces out of Georgia.

The Organization for Security and Cooperation in Europe said Tuesday Russia and Georgia have agreed to allow 20 international military observers into the South Ossetia area.  They are part of the 100 observers the organization plans to deploy.

Earlier, Russia and Georgia exchanged prisoners taken during the last two weeks of conflict.  A Georgian government official said the exchange in the village of Igoeti included five Russians and 15 Georgians.

Meanwhile, Georgian authorities say Russian forces are holding about 20 other soldiers captured in Poti.  The officials again reported the Russians blowing up and destroying Georgian facilities in the port and at the base in Senaki to the northeast

Russia sent tanks and troops into Georgia earlier this month, saying it had to protect Russian citizens after Georgia sent forces into South Ossetia, a breakaway Georgian region that favors Russia.

The Georgian operation was aimed at bringing the area back under Tbilisi's control.

Russian President Dmitri Medvedev warned Georgian authorities Monday that they face punishment for the incursion.  Earlier, Georgian President Mikheil Saakashvili expressed readiness for talks with Moscow once Russian troops leave Georgia.

Some information for this report was provided by AFP, AP and Reuters.