Wreckage has been found on the seabed during a search for a Royal Navy Lynx helicopter which went missing 17 miles off the Cornish coast, the Ministry of Defence has confirmed.

None of the four air crew in the helicopter has yet been located.

The Lynx helicopter went missing yesterday at 7.20pm while engaged on a search mission; sailors on a RN frigate in the area, off the Lizard Peninsula in Cornwall, had reported hearing cries for help from the water.

The helicopter suddenly disappeared from the radar screens, and failed to respond to subsequent radio calls. A Royal Navy spokesman said no mayday had been received from the Lynx.

A Royal Navy Sea King helicopter from RN air station Culdrose, in Helston, which had been helping with the man-overboard search, immediately diverted to look for the missing Lynx, and was joined shortly afterwards by a second Sea King from Culdrose.

A third Sea King, from RAF Chivenor, was also scrambled, and a French maritime patrol aircraft provided assistance.

Type 23 frigates HMS Montrose and HMS St Albans also joined the search, and aircraft carrier HMS Illustrious arrived at around midnight to act as on-scene command platform and a forward refuelling base for the helicopters.

The air crews involved in the search stood down for a brief rest at 4am, but were airborne again at first light, around 7.30 am today.

The local lifeboat from Falmouth had earlier been reported to have found wreckage floating on the sea, and as it recrossed a particular area of sea more wreckage was surfacing along with aviation fuel.

Minehunter HMS Pembroke was then brought in to pinpoint the wreckage on the seabed, and although a surface search continues, a salvage vessel is on its way to the scene equipped with underwater cameras.

Conditions in the area when the aircraft was lost were said to have been relatively benign, and although the water was cold, the air crew would have been wearing protective clothing.

The Lynx is one of the mainstays of maritime aviation for the Royal Navy, and the aircraft has for many years provided the ship’s flight for deployed frigates and destroyers.

The MOD spokesman said that their thoughts and prayers were very much with the families of the missing air crew at this difficult time.