More than 300 front-line staff have signed a petition calling on the region's under-performing ambulance service to stop putting lives at risk by sending cars to life-threatening emergencies.

Medics at the East of England Ambulance Service say their bosses are using a 'loop hole' to claim a key response target by sending Rapid Response Vehicles (RRV) to 999 calls.

Trusts are supposed to get an ambulance to 95pc of the most urgent cases within 19 minutes as part of government targets.

However, front-line staff say the region's ambulance service is claiming the target by sending RRVs to emergencies, when a double staffed ambulance is needed.

More than 300 staff that work for the East of England Ambulance Service have signed a collective grievance calling on management to only claim the A19 target when a transportable resource arrives.

Front-line staff spoke of their frustration at arriving at an emergency in a car and having to wait hours for a back-up ambulance to arrive to take a patient to hospital.

The grievance comes after a review by Anthony Marsh, CEO of the West Midlands Ambulance, said that the East of England Ambulance Service had too many RRVs at times.

A spokesman from the Unison regional branch committee said that last year only 7pc of category A patients were able to be taken to hospital by RRVs. However, every time a car arrives at a 999 call, it is recorded as hitting the A19 target.

'Decisions have been made to put more cars on and it is causing patient harm. A lot of staff feel the board have focused on hitting that target, regardless of patient need and if we send a car to a stroke patient, they need to get to hospital quickly,' the spokesman said.

A spokesman for the trust said: 'Our chief executive, Andrew Morgan has said that he believes that the A19 definition should be reviewed nationally and would welcome a more transparent target which reflects the patient's need and experience.

'We are also looking at the possibility of developing a Red 19 Transport measure. This will be based on the time it takes to get an ambulance to those red calls that are actually conveyed to hospital. This is very different to the current A19 definition, but we believe that this would give a much truer picture of performance and service to patients.'

The collective grievance on the A19 target comes as staff met with bosses yesterday over another official grievance over understaffing in North Norfolk.

Norfolk paramedics met with health ministers Norman Lamb and Earl Howe earlier this year over their concerns about the A19 target 'loop hole'.

They are also leading a campaign and have set up an e-petition calling for changes to a key response target. For more information, visit www.changeA19.org or sign the e-petition at epetitions.direct.gov.uk/petitions/42759