A medical union is stepping up industrial action at several hospitals in an ongoing dispute over wages.
Radiation treatment specialists were not working overtime or were refusing to use technology at the Canterbury, Southern, Auckland and MidCentral District Health Boards (DHBs).
APEX union members at the Capital and Coast and Waikato District Health Boards were now refusing to work in the evenings or through the night.
The action was due to end next Tuesday.
Hospitals said patients would be contacted if there would to be any disruption to their treatment.