One Sri Lankan solder was killed and 11 were injured in a clash with Tamil Tiger rebels in the far north of the island, the military said on Saturday, adding that it believed the Tigers had suffered heavy casualties.
The incident in the northern district of Vavuniya, which borders rebel territory, is the latest in a long string of land, sea and air clashes in recent months.
It came three days after the government declared it had driven the Liberation Tigers of Tamil Eelam (LTTE) from their last jungle stronghold in the east after months of fighting in which the military has had the upper hand.
"The LTTE were firing mortars and artillery and we confronted them ... there are a lot of LTTE casualties," military spokesman Brigadier Prasad Samarasinghe told Reuters.
"We also had one soldier killed and 11 injured," he said.
Sri Lanka has been gripped by renewed civil war since the collapse last year of a ceasefire agreed in 2002, with an estimated 4,500 people killed since last year alone.
The rebels, who are fighting for an independent homeland in the north and east of the island, said on Thursday they aimed to cripple the Sri Lankan economy with major attacks on military and economic targets.
Tiger political wing leader SP Thamilselvan told Reuters in an interview that peace was "not possible" as long as Mahinda Rajapaksa remained president, pouring cold water on international efforts to halt the two-decade conflict.
The military has captured vast swathes of territory from the Tigers in the east in recent months, and now fighting is focused in the north, but analysts say they see no winner on the horizon.
The conflict has killed nearly 70,000 people since 1983.