Military officials in Sri Lanka say the navy has destroyed two Tamil Tiger rebel boats off an island in the country's restive north, killing six rebels. The military says navy patrol boats opened fire on the rebel vessels Saturday after they were spotted heading toward a naval base on Kayts Island near the volatile Jaffna Peninsula.On Friday, officials said the navy destroyed at least seven rebel boats off Jaffna, killing at least 35 rebels. The battles are part of a recent increase in attacks across the country that have left hundreds of combatants dead. On Wednesday, Tamil Tigers posing as fishermen blew up two boats in a suicide attack on a naval base on the southern coast, killing at least one sailor along with 15 rebels.