Long wait times and staff shortages are being blamed for an increase in police callouts to health locations.

Official police figures released to Newstalk ZB show they responded to reports of harassment and threatening behaviour 424 times last year- nearly double four years previously.

New Zealand Nurses' Organisation President Anne Daniels says the state of the health system lends itself to this increase.

"We don't have enough nurses to actually do the job that needs to be done. The waiting for people who are already in extreme distress just boils over into frustration."

Nurses say increased police callouts to health settings don't paint the full picture.

Anne Daniels says reporting an incident takes at least 20 minutes, and often staff don't have time during work hours.

"So when you've got 250-odd people working in one department, nobody's reporting the daily abuse they get. You know there's a problem."

Te Whatu Ora acknowledges high patient volumes, with increasingly complex needs can be exacerbated by staffing pressures.

National's Shane Reti says police data on health setting callouts tallies with what the sector's telling him.

Reti says the numbers don't reflect the frequency he hears about these incidents, so he expects it's unreported.

"They've built a level of tolerance and it's got to be a relatively significant event before they'll document it. That shouldn't be the case either, again, they shouldn't have to normalise that there's some level of criminal behaviour that they have to accept."

Te Whatu Ora says they train staff in de-escalation, encourage reporting of incidents and calling the police if needed.