Sri Lanka's Tamil Tiger rebels on Friday vowed to hang on to a key enclave in the northeast, after the military pounded the area for a fifth night with airstrikes and artillery fire.
The push to retake Sampur opens a new front in the country's more than two-decade civil conflict with ethnic Tamil rebels, who want to establish a separate Tamil homeland.
While areas in the north under the rebels' control were clearly demarcated by a 2002 cease-fire, the northeastern stretch of coast is less clear cut.
Both sides hold pockets of territory, but control over some remains in dispute, including Sampur -- a 50-square-kms patch of land across the lagoon from the strategic Trincomalee naval base.
The military launched a major assault to recapture Sampur on Sunday, saying that in the hands of Tamil Tiger rebels it posed a threat to a base and installations at Trincomalee port.
Rebels in Sampur have been firing artillery and mortars at the port, from where the military transports supplies to its 43,000 troops in northern Jaffna Peninsula.
Sri Lanka's top-ranking military official, Lt Gen Sarath Fonseka, told The Associated Press on Thursday that government troops were then only two kms outside of Sampur.
"This is an area under our control and Tamil people live here. We will not allow the military to invade," S Elilan, the Trincomalee regional leader of the Liberation Tigers of Tamil Eelam, said on Friday.
The exchange of artillery and mortar fire continued in Sampur on Friday, after air force jets took out rebel artillery bases overnight, an official at the Media Center for National Security said.
Casualty details were not immediately known. In recent months Sri Lanka has returned to the brink of full-scale civil war with hundreds of combatants and civilians killed in major military offensives, although neither side has officially withdrawn from the 2002 Norway-brokered ceasefire.
About 220,000 people have been made homeless by the near-daily shelling, airstrikes and artillery fire since April, according to the United Nations.
Tamil Tiger rebels have fought the government since 1983 to create a separate homeland for the country's minority Tamils away from the discrimination of the majority Sinhalese-dominated state.
More than 65,000 people were killed in the conflict before the cease-fire, which most observers say now exists only on paper.