Sri Lankan navy troops have sunk three Tamil Tiger boats off the island's north-east coast, killing at least 15 rebels, the military says.
Officials said the navy fought a three-hour battle with 10 rebel boats.
They said one navy sailor was wounded in the clash, which took place about 60 nautical miles from Trincomalee.
The incident came a day after Sri Lankan troops said they had driven Tamil Tiger rebels from a major base in the east of the island.
"A naval patrol has come across about 10 Tiger boats and our boats launched an attack, and we were able to destroy three rebel craft," Reuters news agency quoted Commander Athula Senaratne, a navy spokesman, as saying.
"During the attack we believe 15 to 18 rebel cadres were killed."
The remaining rebel boats fled, he said.
Violence has been escalating in recent months
There was no immediate comment from the rebels, who have been fighting for decades for a homeland for minority Tamils in the north and east of Sri Lanka.
Despite a ceasefire still being in place on paper, Sri Lanka has been sliding back towards civil war, with more than 4,000 people killed in the past 15 months.
On Tuesday, a Tamil Tiger suicide bomber killed himself and at least seven others in an attack on an army camp in the east of the country, the military said.
The attack followed the rebels' first aerial attack, on a military base, on Monday.
At least one light plane bombed an air force facility next to the international airport near the capital, Colombo.