Government forces captured six Tamil Tiger rebel bunkers along the front lines in Sri Lanka's war-ravaged north and infantry clashes killed 33 rebels and six soldiers, the military said Monday. Fighting has escalated in recent months in the area separating government-controlled territory and the rebels' de facto state in the north. The military has stepped up land and air attacks following the government's recent pledge to snatch rebel-held territory and crush the separatists by the end of the year. Diplomats and other observers say the army has faced more resistance than expected. The latest battles broke out Sunday in the areas of Vavuniya, Mannar, Welioya and Jaffna, said military spokesman Brig. Udaya Nanayakkara. Army troops captured six rebel bunkers near the front lines in Vavuniya after a battle that killed 10 rebels and five soldiers, Nanayakkara said. The same fighting wounded 30 rebels and seven soldiers, and one soldier was missing, the spokesman said.