Government forces fought fierce battles with ethnic Tamil separatists along Sri Lanka's northern front lines in a wave of fighting that killed 43 rebels and four soldiers, the military said Tuesday. The bloodshed came amid weeks of escalating violence in the area, as government troops pushed deep into rebel-held territory, seizing key Tamil Tiger bases and towns that had long been under rebel control. Battles raged Tuesday over the key town of Mallavi, which lies along an important northern road used by the rebels, military spokesman Brig. Udaya Nanayakkara said. "We have taken over about three-quarters of the area," he said. "It's not cleared yet." In the worst of Monday's fighting, troops captured six bunkers in the Nachchikuda area of Kilinochchi region, killing 26 rebels, the military said. Fighting in the area also killed two soldiers, it said.