Colombo, Sri Lanka ? Government soldiers backed by artillery and airpower seized a key rebel enclave in the east Monday, the military said, claiming the first significant territorial change since a cease-fire in the island nation’s civil war four years ago.

But the commander of the ethnic Tamil rebels in the east, S. Elilan, said the battle for the town of Sampur was still raging. “We are fighting them. This is our territory, we can’t let it be invaded by the enemy,” he said.

Recent weeks of near-daily airstrikes and artillery duels between Tamil rebels and government troops shattered the truce on the island just off India’s southern tip, and the military offensive at Sampur was a further escalation in a situation verging on all-out war.

Soldiers entered Sampur on Monday and were clearing the area of land mines and explosives left by retreating rebels, said a military spokesman, Brig. Prasad Samarasinghe.

“We are now fully in control of the area. There may be some resistance, but we are fully in this area,” he said.