Sri Lanka's air force launched attacks on Tamil Tiger rebels along the northern front lines Thursday, while infantry clashes killed eight rebels and two soldiers, AP quoted the military as saying. Air force helicopter gunships hit a rebel fortification in the northern district of Vavuniya, bordering the rebels' de facto state, said air force spokesman Wing Commander Janaka Nanayakkara. He said the attack early Thursday was launched in support of army troops fighting in the area. Details of damage and casualties were not available immediately, he said.