Unite union members at Yorkshire Ambulance Service NHS Trust plan to walk out again on Monday in a row over shift patterns.
The union claims proposed longer shift patterns could lead to staff working for up to 10 hours without a meal break.
The trust has branded earlier industrial action ‘reckless’ and not in the ‘best interests’ of patients.
Union members took industrial action for a period of 24 hours on 1 February, and for four hours on 3 February. They also walked out yesterday afternoon.
A fourth walk-out is planned between 3pm and 8pm on Monday.
Terry Cunliffe, regional officer with Unite, said bosses had refused to meet Unite to resolve the issue.
The trust denies the union’s claims the new shift patterns will impact on patient care.