A fierce sea clash erupted between Sri Lanka's navy and Tamil Tiger rebels off the country's east coast overnight, the military said Sunday, as two days of ground battles killed 28 combatants in the north and east. The sea battle broke out when a flotilla of 15 rebel boats tried to attack naval boats patrolling off Kallarawa, a fishing village in the eastern Trincomalee district on Saturday night, said navy spokesman Cmdr. D.K.P. Dassanayake. He said the battle lasted nearly an hour and that the insurgents were believed to have suffered heavy casualties before fleeing. There was no immediate comment from the rebels, according to a report of the Associated Press.