They are examining reports that the aircraft hit power lines when it came down in fields near the village of Kingscott, near Torrington, North Devon, on Thursday.

One crew member was pronounced dead at the scene and the second was airlifted to hospital but died later. Next of kin have been informed.

The HT1 Squirrel training helicopter was from 670 Army Air Corps Squadron, based at Middle Wallop in Hampshire.

A Ministry of Defence spokesman said: "An Army training helicopter crashed in Devon.

"Sadly, we can confirm that both service personnel on board have died.

"Their next of kin have been informed and have requested a period of 24 hours before further details are released. Our thoughts are with them at this difficult time."

Two rescue helicopters, from RMB Chivenor in north Devon and Portland Coastguard in Dorset, and the Devon Air Ambulance were sent to the crash site, Swansea coastguard said.

Nearly 12,000 homes in the area suffered a power failure at the time of the crash.

Police said power lines came down at the time of the crash but could not confirm the helicopter hit overhead cables.