A Sri Lankan military advance on the stronghold of the rebel Tamil Tigers in the island's northeast triggered heavy fighting that claimed casualties on both sides, the defence ministry said Thursday.  Ground troops backed by warplanes inched towards the rebel capital of Kilinochchi on Wednesday killing 45 guerrillas and wounding 30 more, the ministry said. It placed government troop losses at eight dead and 48 injured. Sri Lanka's army chief said over the weekend that his soldiers had reached the outskirts of the town. There was no immediate comment from the LTTE.