Reduced search and rescue helicopter cover at RAF Chivenor could cost lives, according to campaigners fighting to reverse the proposal.

The Ministry of Defence is planning to cut cover at Chivenor in Devon from 24 hours to 12 hours, from 2012, downgrading it to daytime cover only.

MP Stephen Crabb says he is “deeply concerned” about the proposals.

He said: “Since the closure of RAF Brawdy in 1992 Pembrokeshire has become reliant on the brilliant search and rescue capabilities of RMB Chivenor.

“As the recent rescue of two local divers off Strumble Head demonstrates, this service is a lifesaving and timely resource to tourists, fishermen and residents of the county.

“Everyone understands the need for restraint on public spending in the current climate but this absolutely must not be achieved by cutting life-saving services that are vital to Pembrokeshire.” AM Paul Davies also has grave concerns.

He said: “It’s especially worrying because we have two of Britain’s major ferry ports in our county.

“I dread to think how long it would take if it’s a night-time emergency and they’ve closed Chivenor.”

The MoD has defended the proposals, stating a new fleet of faster rescue helicopters will continue to provide effective coverage.

Future night-time cover in Pembrokeshire and the west will be provided by RAF Valley, Anglesey or Culdrose, in Cornwall, but objectors say the extra distance could put lives at risk.

Ilfracombe Town Councillor Bob Thompson is part of the campaign to keep Chivenor active 24 hours.

He said: “It all comes down to rescue times. If casualties are hypothermic, half-an-hour can be critical.”

Facebook group Keep RAF Chivenor 24 hours has attracted more than 6,400 members. North Devon MP Nick Harvey has also set up a petition against the proposal at www.nickharveymp.com/ petition.

Mr Harvey said: “We accept a new generation of helicopters will have enhanced capabilities, but they won’t have the ability to be in two places at once.”

During Parliamentary questions he asked the Secretary of State for Defence about the implications of the reductions.

Armed forces minister Bill Rammell replied: “The decision to deliver the future helicopter search and rescue service from nine full-time, and three part-time, bases continues to ensure our ability to reach all ‘very high’, ‘high’ and 75% of ‘medium’ risk areas within one hour of take off.”