People in the middle of mental health crises are spending longer than they should in hospitals because they have nowhere else to go.
North Shore Hospital says some of its emergency department patients are being stranded for days at a time.
The Health Minister Andrew Little says investments are being made into community care, and better health workforce planning.
Te Hiringa Mahara, the Mental Health and Wellbeing Commission, monitors and assesses the sector.
Its director of mental health and addiction leadership Tanya Maloney told Jimmy Ellingham the staffing shortages puts backlogs on the services able to be provided.