Sri Lankan forces launched an airstrike against a Tamil Tiger naval base and attacked rebel fortifications in a wave of violence that killed 36 rebels and five soldiers, the military said Monday. The heavy fighting came amid a government offensive against the rebels' de facto state in parts of the north. Top government officials have vowed to destroy the Tamil Tigers and win the 25-year-old war with the separatist group by the end of the year. In fresh fighting Sunday, government troops launched a series of raids against rebel bunkers along the front lines in the Mannar region, military spokesman Brig. Udaya Nanayakkara said. The fighting killed 17 rebels and five soldiers, he said. Rebel spokesman Rasiah Ilanthirayan was not immediately available for comment, but the pro-rebel TamilNet Web site said 11 Sri Lankan troops were killed in the battle. It gave no figures for rebel casualties.