The Sri Lankan military has killed 38 Tamil Tiger rebels and one of its soldiers had died in fresh fighting in the north.
A six-year truce between the state and Liberation Tigers of Tamil Eelam (LTTE) formally ended on Wednesday, opening the way for a military push for the Tigers' northern stronghold and a bloody escalation in a 25-year civil war, analysts say.
On Wednesday 27 people were killed in a bus ambush in the central town of Buttala which the military blamed on the Tigers.
On Friday suspected Tamil Tiger rebels shot and killed 10 people in southern Sri Lanka, the military said.
The Tigers were not immediately available for comment on the fighting. There were no independent accounts of casualties.
The Sri Lankan government scrapped the 2002 truce a fortnight ago. The military said more than 40 civilians, 23 soldiers and over 200 rebels had been killed in fighting since then.
About 70,000 people have been killed since the war erupted in 1983.