(Updates with new military comment, death toll estimate)

COLOMBO, June 19 (Reuters) - Sri Lanka's navy destroyed five Tamil Tiger vessels after coming under attack from two dozen rebel boats off the island's far northern tip on Tuesday, the military said, estimating it had killed dozens of insurgents.

Tuesday's clash at sea off Point Pedro in the northern army-held Jaffna peninsula, which is cut off from the rest of the island by rebel lines, was the latest in a string of land and sea battles and air strikes in recent months.

"We destroyed five boats and damaged 7 to 8 more," said Navy spokesman D.K.P. Dassanayake. "There are more than 40 Tigers presumed dead."

"There were 24 Tiger boats, including four suicide boats," he added. "They were trying to attack our patrol boats, but they failed. We are trying to recover one boat which is drifting."

He said no navy vessels were damaged.

The Liberation Tigers of Tamil Eelam (LTTE), who are fighting for an independent state in the island's north and east and are widely listed as a banned terrorist group, were not immediately available for comment and there was no independent confirmation of what happened or of any casualties.

Fighting is now focused on the north after the military captured the Tigers' eastern stronghold. Around 4,500 people have been killed since last year alone.

The government has vowed to destroy the Tigers militarily, while the rebels say they will step up attacks using a home-grown air force of light planes smuggled into the country in pieces.

Analysts say there is no clear winner on the horizon and fear a conflict that has killed nearly 70,000 people since 1983 could rumble on for years.

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