COLOMBO, Sri Lanka - A suspected Tamil rebel suicide bomber killed at least seven troops and one civilian in a blast at a guard post near the Sri Lankan capital on Sunday, authorities said. Another 17 people, including four civilians, were wounded.

The blast came as heavy fighting in the 25-year-old war between Tamil Tiger rebels and government forces raged in the country's north. The navy said it destroyed a rebel boat and a pro-rebel website reported at least 50 soldiers were killed in a battle near a guerrilla stronghold.

Military spokesman Brig. Udaya Nanayakkara said the suicide bomber forced his way into the Civil Defense Force post in Wattala town and blew himself up. Wattala is a few kilometres north of Colombo.

The blast killed six Civil Defense Force officers, one army soldier and a civilian, while another 13 officers and four civilians were wounded, Nanayakkara said. He blamed the Tamil Tigers.

Dinesh Kumara, 29, was selling vegetables at a nearby fair when the blast went off.

"I heard a huge sound. Then when I ran to the site, I saw flesh and blood splattered all over the area," Kumara said.

An Associated Press photographer at the scene saw several bodies and body parts on the ground.

No one claimed responsibility for the blast, and there was no immediate comment from the guerrillas.

The Tamil Tigers, listed by the United States and European Union as a terrorist organization, routinely deny involvement in suicide attacks. Sri Lankan authorities accuse the separatists of having carried out more than 240 suicide bombings against political, military and economic targets since the early 1980s.

The bombing came amid intensified efforts by government forces to overrun the Tamil rebels de facto northern state. Fighting has escalated in recent months, with the military saying it has captured several rebel bases and large chunks of territory and vowing that the end of the separatist insurgency is imminent.

Navy spokesman D.K.P. Dassanayake said government forces destroyed a Tamil Tiger rebel boat carrying supplies off the island's northern coast Sunday, killing at least four insurgents. He said the vessel may have been carrying fuel.

Rebel spokesmen could not be contacted for comment because communications to much of the north have been severed.

Meanwhile, the rebel-linked TamilNet website reported Sunday that rebel fighters killed at least 50 government troops in fighting Saturday near the rebel stronghold of Mullaitivu.

Nanayakkara dismissed the account and said only nine soldiers were killed in that area.

Both sides routinely exaggerate enemy casualties while underreporting their own. Journalists and independent observers are barred from the war zone, making it impossible to verify battlefield reports released by either side.

The Tamil Tigers have been fighting since 1983 to create an independent homeland for ethnic minority Tamils, who suffered decades of marginalization by successive governments controlled by the Sinhalese majority. The conflict has killed more than 70,000 people.