Further strike action is set to hit Yorkshire Ambulance Service in a bitter dispute over changes to shift patterns.
Members of the Unite union will stage two five-hour strikes on Friday from 3pm-8pm and the same time on Monday.
Unite, which represents 375 ambulance workers, was de-recognised a year ago by management for collective bargaining on behalf of its members after raising concerns that budget cuts could hit patient safety.
Strikes were held in April and June last year and in February this year after the two sides could not reach an agreement.
Unite claims its members will go 10 hours without a meal break and be forced to work 12-hour shifts by changes to working patterns introduced last month.
Unite regional officer Terry Cunliffe said: “It is only a matter of time before someone is seriously injured or killed as a result of staff exhaustion.”
Unison, which represents 4,000 members at the ambulance service, has also now rejected changes to working conditions at the organisation, saying its members have no confidence in chief executive David Whiting and his team.
Bosses at Yorkshire Ambulance Service NHS Trust said the met Unison on Monday and a further meeting would be held next week.
A spokeswoman said: “Monday’s meeting was encouraging and we continue to work together towards a positive outcome.”
The Trust confirmed it had been notified of industrial action by Unite.
The spokeswoman added: “Throughout the periods of industrial action we will be taking steps to maintain operational cover to sustain effective and safe services for patients calling upon us for emergency medical assistance.
“We will continue to make every effort to get to patients as quickly as possible, whilst maintaining high standards of patient care.”