Ambulance workers are to stage a series of fresh strikes in a long-running row over shifts and working hours.
Members of Unite at the Yorkshire Ambulance Trust will walk out for five hours from 3pm on Friday, next Monday and March 29, and from 3am on March 31.
The dispute flared more than a year ago over new shift patterns which Unite said could lead to staff working for 10 hours without a meal break.
The union has warned that patient safety could be affected by staff ''exhaustion''.
Regional officer Terry Cunliffe said: ''Our members have shown amazing solidarity over the last year despite the hard line that an obstinate and blinkered management has continued to take.
''Our members don't take strike action lightly - it has been a last resort - but they feel there are important issues at stake here involving patient and staff safety.''
Unite has 375 members involved in the row, which has already led to several strikes since last year.
The Trust said: ''Once again, this will take place without any concessions for the most seriously ill and injured patients and we remain concerned over this type of action. We have continued to seek ongoing dialogue with Unite through Acas.
''Our focus will continue to be on safeguarding patient care and we are committed to minimising the level of disruption to our services. 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.''