Ambulances run by a private company are being used to answer 999 calls in Leeds.
For the first time, a commercial firm has been brought in by Yorkshire Ambulance Service as it struggles to respond to high demand. The cost has not been revealed.
A Leeds MP has branded the move as “privatisation by the back door”.
Ambulance heads confirmed they had been using the vehicles, from North Yorkshire-based North of England Ambulance Service, since Christmas.
Up to four ambulances, each with two crew members, have been on the road in Leeds and Bradford.
David Williams, director of operations at Yorkshire Ambulance Service NHS Trust, said: “On occasions, such as at times of high demand for our 999 service, our own staff and vehicles can be temporarily supported by a private ambulance service to ensure we provide timely, high-quality care to people in Yorkshire.
“The organisation we are currently working with is registered with the Care Quality Commission, the independent regulator of all health and social care services in England.”
The private firm is used intermittently, depending on demand, when YAS staff cannot cover the extra shifts needed. Use is reviewed on a weekly basis.
Yorkshire Ambulance Service refused to reveal how much using the private service cost, saying this was “commercially sensitive”.
However George Mudie, Labour MP for Leeds East, said: “It’s privatisation by the back door without any consultation or public awareness.”
He criticised the fact that the cost was not being revealed.
“It could be they are covering up for lazy management and not being able to organise their ambulance service properly, so they have an expensive service to get them out of difficulties.
“I would have to be convinced that they are paying less for these than they would for the public service.”
The move comes as health services in Leeds come under pressure from an unexpectedly high demand for emergency care.
A spokesman for Leeds Teaching Hospitals said last Sunday attendances at A&E units at Leeds General Infirmary and St James’s University Hospital reached 628 patients in total - including a significant number who were seriously ill.
“We know demand on services is unpredictable and our staff are very resilient in coping with a sudden influx,” he said.
“Overall, A&E attendances in Leeds have been rising year-on-year over the past five years. We are continuing to appeal to the public to work with us to keep A&E for real emergencies and to consider other treatment options including minor injury units, GP surgeries, pharmacists and NHS Direct.”
Previously Yorkshire Ambulance Service has come under fire for not meeting response time targets - though it has improved its performance in recent years. In 2010, in response to claims it did not have enough staff, bosses said they had recruited hundreds of extra frontline workers.