TBLISI, Georgia — Russia opened a second front in the war on Georgia by attacking pro-Georgian districts of the separatist region Abkhazia.

Russian troops were reported to be advancing on the Kodori Gorge, a foothold of ethnic Georgians in the region. The rebel government of Abkhazia announced a general mobilization of its militia for a state of war.

A senior Georgian official conceded last night that Georgia would not deploy its army to resist the Russian advance. Russia has consolidated control of South Ossetia, the other breakaway region, after Georgian government troops withdrew.

President Saakashvili of Georgia appeared powerless to reverse the Russian push last night as he lamented the heavy aerial bombardment of the Kodori Gorge and a Georgian military base in Zugdidi region, bordering Abkhazia. “We’ve been bombed the whole day,” he said. “The bombing has been intensifying.”

Russian jets raided several Georgian air bases and bombed the Black Sea port city of Poti, near Abkhazia, which has a sizeable oil shipment installation.

Further pressure was exerted from the sea as a fleet of eight Russian naval vessels mounted a temporary blockade of Georgian waters. Ukraine, which has been accused by Moscow of supplying weapons to Georgia, intervened to declare its right to bar the return of the warships to the Ukrainian port of Sevastopol, home of Russia’s Black Sea fleet. A 1997 agreement lets the Russian fleet remain in Sevastopol until 2017.

Russia’s vastly superior air force has inflicted heavy damage across Georgia. Jets struck an aircraft factory and a military airport on the outskirts of Tbilisi, the capital. Residents far from the front line were shaken by the bombing.

A contingent of American troops, which is in Georgia to train troops for service in Iraq, is to fly out of Tbilisi today.