The Liberation Tigers of Tamil Eelam on Saturday sunk a Sri Lankan naval logistic ship at the Trincomalee harbour with the Tiger rebels claiming it was the handiwork of their commandos from 'Kangkai Amaran unit'.

Coverage: War in Sri Lanka

"An under-water explosion damaged and caused logistic vessel A-520 (MV Invincible) to sink at 2.15 am on Saturday while moored at the Ashroff jetty in Trincomalee harbour," a Sri Lankan Navy statement said.

It said no lives were lost due to the explosion.

The A-520 was a merchant vessel built in 1970's and handed over to the Sri Lanka [Images]n Navy, following a court order after it was apprehended while transporting 254 illegal migrants off Tangalle in Southern Sri Lanka in 2003.

The Sri Lankan navy said it was now engaged in extensive search operation in and around the area.

The LTTE, meanwhile, said the underwater attack by Black Tigers was carried out when the supply vessel was loaded with explosives to be transported to KKS Harbour in Jaffna.

The ship was sunk within the first 13 minutes of the attack, the Tigers claimed.

"The 80-meter long supply ship and troop carrier has also been deployed in the Sri Lanka Navy's deep sea operations against Tiger vessels in 2007," it said.

The ship has lately been engaged in naval re-supply service between KKS and Trincomalee.

"Commandos from Kangkai Amaran unit of the Sea Tigers took part in Saturday's mission," the Pro-LTTE website Tamilnet quoted the rebels as saying.

"The unit was named after a senior commander of the Sea Tigers killed by Sri Lankan Army Deep Penetration Unit on 29 June 2001 in an attack in the Mannar district," they said.