Sri Lanka's navy says it has destroyed four Tamil Tiger boats killing at least 14 fighters in a battle off the island's northern coast.

The Liberation Tigers of Tamil Eelam (LTTE) confirmed the clashes, but said it destroyed a naval vessel and a hovercraft.

A naval spokesman said that fighting took place off the northern Jaffna peninsula. 

"Four LTTE attack craft were destroyed, 14 terrorists killed and as many others reported injured in a fierce sea battle that erupted between naval craft and Sea Tigers," the defence ministry said in a statement.

It said at least five senior Tamil Tiger rebels were among those killed.

However, the Tigers, in remarks published on a rebel-affiliated website, said only seven Tamil suicide bombers had died.

It said that 20 Sea Tiger attack craft took part in the battle.

Jaffna is controlled by government forces, but cut off from the rest of the island by LTTE-held territory and supplied entirely by ship or aircraft.

Eleven days ago, the Tamil Tigers used suicide craft  against two merchant ships transporting supplies to the Jaffna peninsula.

Northern offensive

The latest fighting came as government security forces continued their ground offensive against the separatists around the northern town of Kilinochchi, their de facto administrative capital.

The government has said it is confident that it will defeat the Tamil Tigers in the north of the island, after more than 20 years of battling the group which wants an independent homeland for ethnic Tamils.

At least one senior government figure has talked of defeating the rebels militarily within two to three years.

The military has stepped up its offensive in the last three months and says it has steadily seized one LTTE stronghold after another and is within striking distance of Kilinochchi.

Tens of thousands of people have died since the LTTE launched its campaign in 1972.