A pro-Tamil legislator in Sri Lanka [Images] was shot dead in Colombo on Friday by a lone gunman amid escalating violence in the island nation.

Member of Parliament Nadarajah Raviraj died in hospital while his bodyguard Lakshman was dead on arrival at the national hospital, police said.

A former mayor of Jaffna in the war-torn northern peninsula, Raviraj, was on his way to work in rush-hour traffic in Narahenpita when an unidentified person riding a motorcycle gunned him down and escaped.

The Tamil National Alliance legislator was known for being an outspoken critic of the security forces, regularly appearing on television talk shows to vent his views.

His party is widely regarded as a proxy of the Tamil Tiger rebels. He is the second TNA legislator to be killed in the past year.

Around Christmas legislator Joseph Pararajasingham was gunned down in the east of the island and assassins have not been arrested to date.

The incident took place as LTTE rebels engaged security forces in a fierce pre-dawn battle at sea on Friday north of the north-eastern port town of Trincomalee.

Meanwhile, military officials said two boats belonging to the Sea Tigers were destroyed as they tried to run down a navy gunboat early on Friday morning.

They said the boats were rigged with explosives and were most likely primed to attack the Sri Lanka navy.

At least six people are believed to have died in the explosion.

On Thursday, two naval Dvora gunboats were attacked and wrecked by rebels with 31 people dead on both sides.

The LTTE said they had taken four navy sailors captive and had the dead body of another sailor after Thursday's incident.

LTTE spokesman Rasiah Ilanthiriyan said that rebels had boarded one of the Dvoras, had taken all weapons and ammunition aboard, including a 23 millimetre cannon, five light machine guns, a grenade launcher and four 'five-zero' guns and then set the craft on fire.

Ilanthiriyan denied government charges that the LTTE had been targeting a civilian passenger ferry carrying 308 passengers from the north-eastern port of Trincomalee to Jaffna peninsula.

The fighting at sea erupted as the United Nations, the United States and Norway lambasted the government for its shelling of a rebel-held area in Vakarai, which left at least 65 Tamil civilians dead.

The US State Department said an independent investigation into the incident was vital. President Mahinda Rajapakse said he regretted the number of civilians who died.