Five people on board a supply vessel of Oil and Natural Gas Corporation were missing after the ship sunk off the Mumbai coast on Monday.

Of the 14 people on board, nine were rescued immediately, ONGC [Get Quote] Chairman and Managing Director R S Sharma told PTI.

Offshore supply vessel Samudrika-10, one of the 14 such vessels owned by ONGC, went down in the Arabian Sea at 1230 hours.

The vessel was operated by private agency Seacal and all 14 people on board were its employees. Rescue operations by Coast Guard and an ONGC team were on.

"Helicopters have been pressed into service to locate the missing," Sharma said adding, operations of the Mumbai High fields -- the country's largest oil and gas field -- will not be affected.

The accident is reminiscent of an incident in July 2005 when a similar supply vessel sank after colliding with an oil station of the public sector company in the Mumbai High fields.

An ONGC press release said that Samudrika-10, operating in Bassein and the satellite fields of ONGC, started taking in water and sank around 1230 hours.

"Out of the 14 manifested crew members, nine have been rescued. All out efforts are being made with the help of one chopper and three vessels in search and rescue operations," it said.

Samudrika-10 was operating in the sea at 56 nautical miles from Nhava Supply Base of ONGC at the time of the incident.

"This being one of the fleet of around 60 OSVs deployed for material supplies to offshore operations, loss of the OSV will not have any significant impact on operations. The insured value of the vessel is likely to be in the range of $2-3 million only," the statement said.