Sri Lankan military officials said the bodies of five sailors were
recovered while a search was still underway for the other 10 who were missing and presumed dead after the pre-dawn attack off the northeastern port of Trincomalee.
"There were two gunboats in the area and one saw the other being attacked," defence ministry spokesman Prasad Samarasinghe said.
"The boat exploded and we believe it is an LTTE (Liberation
Tigers of Tamil Eelam) suicide attack."
Two officers and 13 sailors were aboard the Israeli-built Dvora
class gunboat that was on a routine patrol outside Trincomalee harbour, a main base for the navy, the spokesman said.
The incident just outside Trincomalee naval harbour in the early hours of Saturday is the latest in a series of attacks against the military by the Tamil Tiger rebels.
The attack came as Sri Lanka's foreign minister, Mangala Samaraweera, wrapped up a visit to Washington designed to step up international pressure on the Tiger rebels.
Samaraweera said Colombo was still willing to walk that extra mile for peace."
Speaking to reporters in the US capital he said: "We want to bring international pressure on the LTTE to come and sit with us at the table to discuss the weaknesses of the cease-fire and find ways and means of strengthening it so these dastardly acts do not happen again."
In recent weeks Sri Lanka has seen both sides blaming the other for a series of deadly attacks, with fears growing of a return to all-out civil war.
Seeking a separate homeland for ethnic Tamils, the LTTE rebels have fought a bloody insurgency since the early 1980s, resulting in the death of thousands.
Speaking in Washington Samaraweera urged the international community to press the LTTE "as much as possible, as hard as possible" to return to ceasefire talks.
Promising that the government would keep talking to avoid war, he condemned the rebel movement as a "brutal terror machine" that had over past decades killed leading Sri Lankan Tamils as well as majority Buddhist Sinhalese.
The United States banned the LTTE in 1997 and US forces
have been training Sri Lankan troops, but diplomats in Colombo say there is no chance Washington would wade in militarily if
the violence spirals into war.
State Department spokesman Sean McCormack told reporters
that Secretary of State Condoleezza Rice had praised the Sri
Lankan government for its restraint in the face of the Tamil
Tigers' provocations and vowed to work with Sri Lanka to defeat terrorism and promote peace.
Samaraweera also warned that while the government remained patient, Colombo was concerned that "there will come a point
where the public would be provoked into actions which the government may not be able to control."