A navy vessel detected several boats of the Liberation Tigers of Tamil Eelam (LTTE) off the coast of Mullaitivu sparking a battle that both sides said lasted nearly five hours.
"On completion of the confrontation only 14 craft were seen fleeing...
nine sank along with the crew," Sri Lanka's defence ministry said, adding it was "believed more than 70 Sea Tigers were killed and many were injured."
The LTTE said only three of its fighters were killed and that no boats were lost.
"On our side, we lost three of our cadres killed," LTTE spokesman Rasiah Ilanthiriyan told AFP from the Tiger offices in the rebel-held town of Kilinochchi in the island's north.
He said the Tigers damaged two naval craft.
"Both naval craft had to be towed away," Ilanthiriyan said, adding, "we don't know navy casualties."
He also denied naval claims that the Tigers were operating a flotilla transporting supplies and cadres to the eastern district of Batticaloa and said they were on a routine patrol.
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