Calls for more mental health support, as family violence and mental health incidents, bog police down.

It comes after Christchurch officers took 90 minutes to attend an incident on Saturday, which left three nurses in the emergency room.

READ MORE: Nurses assaulted after police take 90 minutes to respond

After being told the violent patient had been restrained, Police decided to attend a more 'urgent' mental health incident first.

Police Association president Chris Cahill says on average, a frontline police officer spends half their time dealing with family harm and 20 per cent attending mental health incidents.

He says the remainder is left for duties the public expect officers to be doing.

"Attending things like burglaries or responding to request for urgent assistance around motor accidents."