UP to 500 ambulance workers will strike for two days next month, in an escalating row over staffing changes.

The union Unite said its Yorkshire Ambulance Service members feared for the quality of the service after the trust which covers 6,000 square miles introduced emergency care assistants to work alongside paramedics.

The industrial action follows about 450 members of the union staging a 24-hour walkout last month.

Unite regional officer Terry Cunliffe said the service was deteriorating and public safety was being affected.

He said the strike action was being launched after repeated approaches to the trust's executive and board members, with Acas and independently, had been rebuffed.

He said: “No emergency worker ever wants to go on strike. But if the trust is refusing to meet to discuss members’ concerns they are left with little choice.”

The union said its members would strike for 12 hours on June 7, followed by a 24-hour walk-out on June 22, unless progress is made in negotiations.

The NHS trust ended its voluntarily recognition of Unite for collective bargaining in February.

The Yorkshire Ambulance Service NHS Trust said it was trying to maintain a high quality of care while saving £46m over five years and that it had met with the union and employment dispute resolution service ACAS.

A trust spokesman said other ambulance services had successfully been using emergency care assistants for a number of years.

He said: ““Emergency care assistants do not replace clinicians. They are not expected to operate at the same level as a fully-qualified clinician and the training they receive is wholly appropriate to the role they are required to deliver.”