Russia has denied claims that one of its fighter planes shot down a Georgian drone, and criticized Georgia for conducting flights in what it called a "conflict zone."

Georgian military officials accused Russia Monday of sending an Air Force fighter jet to shoot down the drone over the breakaway region of Abkhazia.

Georgian President Mikhail Saakashvili said he telephoned his Russian counterpart, Vladimir Putin, and told him to stop what he called "aggressive" attacks inside Georgian territory.

According to the Kremlin press office, Mr. Putin "expressed bewilderment" over the the Georgian military flights and warned the flights were escalating regional tensions.

Earlier, the Russian Air Force said Russian pilots were not on duty when the drone was shot down.

In Washington, U.S. State Department spokesman, Tom Casey said the United States is very concerned about the situation. He repeated U.S. support for Georgia's territorial integrity, and said U.S. officials are seeking clarification from both sides.

Georgian Foreign Minister Davit Bakradze visits Washington Tuesday, seeking U.S. help in preventing Russia from undermining Georgia's claim to the breakaway regions of Abkhazia and South Ossetia.

The drone shoot-down came despite separate Russian diplomatic efforts to ease bilateral tensions stoked by a recent Russian decision to strengthen ties with the breakaway regions.

Moscow today restored postal links and money transfers with Georgia, ending a cut-off imposed in 2006 after Georgian authorities briefly arrested four Russian military officers accused of spying.

Russia announced last week that it will increase cooperation in trade and culture with the two breakaway regions, triggering Georgian and international condemnation.

Abkhazia and South Ossetia declared independence from Georgia in the early 1990s, prompting the deployment of Russian peacekeepers in the regions.

Georgia has repeatedly accused the peacekeepers of supporting the separatists and vowed to bring both areas back under central government control.

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