A Sri Lankan navy cargo vessel has been sunk by a Tamil Tiger attack in the eastern port town of Trincomalee.

The attack, confirmed by the Sri Lankan military, came shortly after 11 people were killed on Friday night by a bomb in a cafe in Ampara.

Local elections are being held in Ampara for the first time in 20 years.

The area was retaken from Tiger control last year. 

The Liberation Tigers of Tamil Eelam (LTTE) said its Sea Tiger commandoes launched the pre-dawn attack on the boat as it was being loaded with explosives to be transported for troops fighting in the island's north.

The separatist Tigers have been battling for a homeland for ethnic Tamils since 1972 and control much of the north and east of the country.

The Sri Lanka navy confirmed that the MV Invincible A-520 logistic vessel sank when an underwater explosion ripped through it. 

It claimed the 65m vessel was empty at the time.  

"No lives were lost due to the explosion," a defence ministry statement said.  

Under a million residents in Batticaloa, Trincomalee and Ampara will cast their ballots on Saturday to elect officials to run the eastern provincial council.

Source: Agencies