Colombo: At least 30 guerrillas and six soldiers died after Tamil Tiger rebels attacked a Sri Lankan navy base on Saturday, which triggered a naval and helicopter battle.

The sea attack took place in the northwest area of Mannar, where the navy maintains several small bases. Parts of the area are under government control.

Three suspected rebels in diving gear were seized at a beach in Pamunugama, north of Colombo. The men were arrested but took cyanide capsules and were taken to hospital.

Government planes hit targets neat the Liberation Tigers of Tamil Eelam (LTTE) stronghold of Kilinochchi through the night.

A military spokesman said, "Eight LTTE boats destroyed by naval fire. Six navy sailors died. We have around 30 deaths of LTTE. Navy and police have witnessed the bodies. One civilian succumbed to his wounds. Three naval craft slightly damaged."

Attack helicopters were working with the military in searching for more rebel crafts, he said.

The violence comes after an attack on a bus earlier this week that killed 64.

The Tigers have denied the bus attack, which was the worst incident since a truce in 2002 halted two decades of war.

There has been a sharp increase in violence since early April and almost 700 people have died this year.