COLOMBO, June 19,2007 Sri Lanka's navy sank one Tamil Tiger boat and disabled two others in a naval battle off the island's far northern tip on Tuesday, the military said, adding that between 15 and 20 insurgent boats had attacked them. "They are retreating," said military spokesman Brigadier Prasad Samarasinghe. "Five clusters of rebel boats attacked our patrol boats, none of our boats were damaged." The Tamil Tigers were not immediately available for comment.