AMBULANCES operated by a private firm are being used to respond to 999 calls in North Yorkshire.

Yorkshire Ambulance Service NHS Trust has employed Malton-based North of England Ambulance Service to provide two vehicles to answer emergencies in the county during periods of high demand since Christmas.

The trust, which has a fleet of 320 ambulances and 210 rapid response vehicles, said it had paid the firm to ensure it provided timely, high-quality care, after being criticised in 2010 for failing to meet response time targets.

A trust spokeswoman rejected claims that the move represented “privatisation of the NHS by the back door”, saying the number of private ambulances hired was “a drop in the ocean”.

She said: “The private ambulances are brought in at times when the projected need for services is higher, such as during cold spells, and is part of our winter strategy to provide for a population of five million.”

North of England Ambulance Service said it had undergone a rigorous tender process before being selected to respond to 999 calls. A spokesman for the firm, which was launched in 2008 and is registered with the Care Quality Commission, the independent health services regulator, said its response teams provided the same level of care as NHS ambulances. He said: "It is fantastic for us to have the opportunity to work alongside the Yorkshire Ambulance Service in providing care for the people of Yorkshire."