Six sailors from the fast attack craft (FAC) were rescued by another boat patrolling the waters off the Tamil Tiger stronghold of Mullaitivu district, spokesman D. K. P. Dassanayake said.
"The officer in charge and five others from the FAC were rescued," Dassanayake said.
"One of them said the craft started taking in water after a huge explosion. They got into a life raft."
The pro-rebel Tamilnet.com website reported that the Dvora-class fast attack craft was sunk in a suicide attack launched by the Liberation Tigers of Tamil Eelam (LTTE).
Three "Black Sea Tigers," or suicide bombers, perished in the attack, Tamilnet said quoting Tiger sources.
However, Dassanayake denied there had been any confrontation with the Tigers and insisted that the navy vessel was sunk in a sea mine blast.
A search was underway for the other 10 crewmen after the pre-dawn blast, which occurred as attack craft were patrolling for suspected Tamil rebel activity.
Clashes between suspected Tamil T