Suspected Tamil Tiger rebels rammed an explosives-laden fishing boat into a Sri Lankan navy vessel off the northwestern coast early Saturday, killing at least 15 sailors and leaving three missing, officials said.

The assault near the port of Trincomalee was the latest in a series of attacks against government troops by suspected rebels, who are campaigning for a homeland for Sri Lanka's 3.2 million ethnic minority Tamils.

Navy spokesman Cmdr. Jayantha Perera said 15 sailors died and that search and rescue operations were on to find the three missing. Another navy boat, which was at a distance, escaped the impact of the explosion.

The pro-rebel Web site, TamilNet, reported the incident but did not mention casualties or who was responsible for the attack.

But Sri Lanka's army blamed the Sea Tigers, the naval wing of the Liberation Tigers of Tamil Eelam.

"In one of the worst Tamil Tiger (LTTE) attacks, LTTE Sea Tigers early this morning....blew up a Naval vessel Fast Attack Craft," a statement posted on the army's Web site said.

The Tamil Tigers carried out several attacks against naval vessels using explosives-packed fishing boats before a cease-fire in 2002 halted the rebels' two-decade independence war.

A similar attack in Trincomalee harbor in 1995 triggered full-scale hostilities, dashing a brief truce.

The insurgents want a separate state for the country's 3.2 million Tamils, claiming discrimination by the majority Sinhalese, who number about 14 million.

Trincomalee, which has a strategic port and a base for the Sri Lankan navy, has been tense this week after five ethnic Tamils died. The military has said the men accidentally blew themselves up in a botched grenade attack on a military patrol, but the rebels said the men came under attack from government forces.

A formal government inquiry has been ordered into the killings.

The Norwegian official who brokered the 2002 cease-fire, Erik Solheim, has urged the government and the rebels to resume peace talks immediately. Six rounds of peace talks were held until 2004 when they broke down over rebel demands for autonomy.

Solheim is scheduled to visit Sri Lanka in late January.

U.S. Undersecretary of State Nicholas Burns also plans to visit Sri Lanka to encourage negotiations between the two sides, State Department spokesman Sean McCormack said Friday. No date for the trip has been announced.

Violence has worsened in the country since November's election of Sri Lanka's new president, Mahinda Rajapakse, who campaigned on a promise to take a tough line in negotiations with the rebels. Rebel leader Velupillai Prabhakaran has warned the Tamil Tigers would intensify their struggle if their grievances were not addressed.

The 2002 cease-fire halted two decades of a civil war that has killed more than 65,000 people since 1983. But last month 45 soldiers were killed and 71 wounded in ambushes blamed on the rebels; government troops killed seven suspected rebels.

The two sides have also traded accusations about the slaying of a pro-rebel lawmaker at Midnight Mass on Christmas Eve. And in August, former Foreign Minister Lakshman Kadirgamar was assassinated by suspected Tiger gunmen.

(Source: AP/CNN)