The Police Association says frontline officers are dealing with a big increase in mental health incidents and wants better intervention to prevent people from reaching breaking point.
Officers were called out 10,734 such incidents in the past year, an increase of 56% on 10 years ago, and the union says that ties up resources.
Police Association president Greg O'Connor says in many cases, the mental health system has failed people and they are either not in the system or on medication.
Mr O'Connor says police intervention is needed when things go wrong.
Canterbury district commander Superintendent Gary Knowles says a pilot programme has been operating successfully in the Christchurch central police station where psychiatric nurses are employed 24 hours a day.
Mr Knowles says that programme is working well and officers are training on the job.