Private ambulances used for Leeds emergency calls
An ambulance service is using vehicles and staff provided by a private company to answer emergency calls because of staff shortages.
Yorkshire Ambulance Service has said it could call on up to 13 ambulances, each with two crew members, to cover staff shortages.
The ambulance service declined to reveal the cost of the arrangement in Leeds.
The union Unison criticised the measure.
Yorkshire Ambulance Service said it had brought in the private ambulance cover supplied by the North Yorkshire-based England Ambulance Service.
Vince Larvin, of the Yorkshire Ambulance Service, said the move was to maintain emergency cover.
He said: "It's a resilience measure for us in the Yorkshire Ambulance Service around the fact that we're obliged to provide a safe level of cover and I'm pleased to say that for the first time in five years since we became a trust we're achieving the national standards.
"In terms of having gaps and responding to some massive surges that we've had recently we've taken on some private providers to help us keep providing that level of specialist cover that we've done so well for the rest of this year.
"These private providers are accredited by the Care Quality Commission so we're absolutely satisfied that the standard of care they provide is good."
Mr Larvin said the recruitment of more staff by the service depended on the budget settlement they reached for the next financial year.
He said he was not prepared to divulge the cost of the additional ambulances: "We can't go into the details of (the contract) but it's a very competitive price, we're mindful of the cost.
"It's not something that as far as we're concerned in the future is going to be a main part of our business plan."
Unison official Ray Gray said: "It's not how an ambulance service should be run."
He said he was concerned the private ambulances did not have the same access to NHS details or health service navigational equipment.
"We need dedicated professionals who know the area they're working in and have the right equipment to do the jobs," he added.