New Delhi, Nov 7 (IANS): Four navy personnel, including an officer, remained missing Friday while the navy launched full-scale search and rescue (SAR) operation after its torpedo recovery vessel (TRV) sank off the Visakhapatnam coast Thursday night.

A board of inquiry headed by a captain has been constituted to investigate into the circumstances leading to the mishap.

Navy chief Admiral R.K. Dhowan, who is on an official visit to Seychelles, has cut short his visit to reach Visakhapatnam.

A defence ministry release said that nine ships of the Eastern Fleet and a few aircraft, including Boeing P8I, Dorniers, Sea King 42C, and Chetak helicopters have been deployed through the night to search for the missing personnel.

"At the time of the incident, there were 29 personnel on board. One sailor has lost his life during the rescue operation and four personnel (one officer and three sailors) are still reported missing," the release said.

It said that as per the initial reports, the probable reason for the sinking of the vessel seems to be ingress of sea water (flooding) in the engine room and aft steering compartment of the vessel.

Sources said the likely cause was "material failure".

The ship was built by Goa Shipyard Limited in 1983.

TRV is an auxiliary vessel used to recover practice torpedoes fired by fleet ships and submarines.

Navy has witnessed a series of accidents over the past year. Earlier this year, the then navy chief Admiral D.K. Joshi resigned taking moral responsibility for "the accidents and incidents".

In August last year, 18 crew members on board - three officers and 15 sailors - were killed when blasts ripped through the torpedo compartment of the INS Sindhurakshak while the submarine was berthed at the Mumbai harbour.

Two sailors died and seven members of the 94-strong crew were evacuated in February this year after inhaling smoke aboard the diesel-powered INS Sindhuratna submarine following a fire on board.