An under-pressure ambulance service is asking medical professionals to join an emergency responder scheme to tackle urgent calls on a voluntary basis.

The East of England Ambulance Service NHS Trust (EEAST) will be trialling an initiative which sees staff volunteering to respond to the most urgent cases in their communities out of hours.

Last month, it was revealed response times in the East of England Ambulance Trust (EEAST) were more than double the national target.

Union leaders have criticised the latest scheme saying "doing extra work for free" is not the answer, but EEAST said the idea came from staff.

An EEAST spokesman said: "It is proven that fast response times help improve hospital survival rates and this is an additional way for us to reach patients who need our help.

"Following successful trials elsewhere in the country, we are pleased to introduce this programme and we want to thank our committed staff for taking the initiative to suggest it."

A similar scheme for Community First Responders was introduced in 1997 and the EEAST say the hundreds of thousands of hours they volunteer every year saves many lives and also supports community education.

However, the initiative has come under fierce scrutiny from the union, who believe it may promote burnout amongst already stretched medical professionals.

UNISON EEAS branch chair Glenn Carrington said: "The ambulance service is under enormous and unprecedented pressure.

"We're struggling to cope with the huge A&E waiting times, spending hours waiting outside full hospitals unable to answer new calls.

"There's no doubt that urgent action is needed but asking already stretched staff to start doing extra work for free is not the answer.

"Ambulance crews do hugely stressful and tiring work, we need to take time off to relax and recover on rest days, not sit by the phone ready to rush off to another emergency."

An EEAST spokesman added: "The idea for this scheme came from our staff, as they wanted us to give them the opportunity to donate their spare time to support more patients.

"It is an entirely voluntary initiative, in which expert clinicians with local knowledge can rapidly respond to emergencies in areas they know."

They will be opening formal applications to members of staff shortly, once they have identified the locations in which the scheme will be trialled.