New Delhi, Dec 31 (IANS): The reason behind the sinking of a torpedo recovery vessel off the Visakhapatnam coast is still not known, but Defence Minister Manohar Parrikar said the navy personnel who died in the accident were trying to save the ship.

The minister during an interaction with journalists Tuesday night said the four navy personnel did a commendable job.

"The navy personnel who died in the TRV accident were actually trying to save the ship. They did a commendable job and we need to laud them," Parrikar said.

He said they have not yet been able to find out the reason behind the accident.

"A ship must not sink so fast, there was something wrong. But it is not in a metre of mud, so even if there is a hole in the bottom, we cannot see it," he said.

Parrikar said efforts will be made to make the ship float again so that the reason behind the accident can be known.

Indian Naval Torpedo Recovery Vessel IN TRV A 72 sank off Visakhapatnam Nov 6.

The ship had sailed for a routine mission with 29 personnel, including six from the Naval Science and Technology Laboratory in Visakhapatnam.

While returning to Visakhapatnam after completion of mission, the ship reported flooding in her steering gear compartment.

According to a reply by Parrikar in the Lok Sabha, 24 personnel were rescued alive, the body of one serviceman was also recovered. At present, four personnel remain missing.