Five of the Tamil Tiger fighters attacked Sri Lankan troops who were searching for hidden weapons and ammunition in the port of Jaffna, a defence ministry official said on Wednesday. They died in the gun battle that followed but no soldiers were killed, he added.
The navy said the Tigers had mingled with civilians on an islet to the west of Jaffna where their Sea Tiger naval arm had landed fighters last week.
Separately on Wednesday, three separatists who had attacked a police patrol in eastern Sri Lanka were killed, a military spokesman said.
Fighting in the government-held Jaffna peninsula - which borders Tiger-held territory - died down on Tuesday but soldiers continued to carry out search operations along the frontline.
Sri Lankan warplanes carried out three daylight raids on Tamil positions inside the Tiger-held Wanni region, just south of the Jaffna peninsula, military officials said.
"Several targets were taken by the air force, but we don't have details yet," a military official said.
The defence ministry said troops were consolidating their control in the district, adding that there had been sporadic long-range firing but no close-quarter fighting.
An indefinite curfew is in place on the peninsula and thousands of people have taken refuge in churches.
The curfew was eased briefly and then reimposed after the military distributed rice and lentils to civilians who had been trapped by the fighting, a military official said.
The military said it killed at least 24 separatists on Tuesday at the eastern edge of the peninsula and had beaten back a Tiger offensive against the town of Jaffna.
Jayawardena said the Liberation Tigers of Tamil Eelam (LTTE) were attempting to retake Jaffna which was part of a de facto separate state they ran from 1990 to 1995 until troops drove them out.
In the latest fighting, at least 150 soldiers were killed and more than 300 wounded. The military said it had killed more than 250 Tigers and wounded about 300 but the separatists said only 22 had died.
Towns in the Tiger-controlled north and east observed a strike on Wednesday to protest against a government bombing raid which the Tigers said killed 61 children on Monday.
Similar strikes took place in Muslim towns along the east of the island to protest against alleged Tamil Tiger attacks against Muslims who form the second largest minority.