Health worker unions are furious Worksafe is refusing to investigate how seven Waitakere Hospital nurses were infected with Covid-19.
Worksafe says the Waitemataa DHB has already investigated and made changes.
But unions representing nurses, doctors and almost every other staff member at the hospital say the decision is unacceptable.
They plan to take up the issue with Ministers and to try to have the decision overturned.
A spokesperson for the union which represents junior doctors, Deborah Powell, told RNZ health correspondent Rowan Quinn an external investigation is needed.