Paramedics are being balloted for strike action in a long-running dispute over working conditions and patient safety.
The Unite union, which represents 378 staff at Yorkshire Ambulance Service NHS Trust, claims patients are being put at risk because of cost-cutting at the organisation.
The union says semi-skilled care assistants are being sent to 999 call-outs without adequate training.
Unite also claims its members have been left without adequate rest breaks after changes to working conditions were imposed without proper consultation.
The union was de-recognised by the ambulance service for negotiating on behalf of its members in February 2013 after publicly raising safety concerns.
Terry Cunliffe, Unite’s regional officer, said: “We are balloting again for industrial action at the trust to secure the right for Unite to be recognised as a legitimate trade union in order to protect patient and staff safety.”
Unite is required by law to hold another ballot to secure a mandate for further strike action in the dispute, which started 18 months ago.
A serious of strikes after been held by Unite since April 2013.
Yorkshire Amblance Service has insisted that patient care is not being compromised by changes at the organisation.
Chief executive David Whiting said: “Patients’ needs are at the heart of everything we do and our absolute focus is to ensure that we continue to deliver a safe, responsive and high quality service to our patients.”