At least nine vessels were destroyed in a naval clash Thursday between Tamil rebels and Sri Lanka's navy off the northern coast, officials said. Rebel military spokesman Rasiah Ilanthirayan told The Associated Press that fighting broke out when navy vessels disturbed the rebels' "routine naval exercises."A Defense Ministry official, however, said about 16 rebel boats, including explosive-laden suicide boats, attacked a navy patrol and sank one boat. The navy, assisted by the air force, retaliated, destroying eight rebel boats, the official said on condition of anonymity due to policy. One naval craft was destroyed in the battle and another was damaged. There was no independent account of the incident, and no details of casualties were immediately available.