The Police Commissioner has acknowledged the alleged treatment of two teens, who claim they were traumatised after being strip-searched by officers, was inappropriate.
The 14 and 16-year-old cousins last week told a Wellington newspaper they suffered long-term effects from the ordeal, in which they were kept in a cell for 36 hours in January over a complaint about an attack on two other teenage girls.
The girls were taken to Upper Hutt police station, strip-searched and placed in individual cells ahead of their court appearance, they alleged.
One of the girls had to express breast milk into a sink after being separated from her baby. They were not given toilet paper and were refused contact with their families and lawyers while in custody, they told the newspaper.
In his blog today, Police Commissioner Peter Marshall said he was "left shaking my head'' over the allegations of the girls' treatment by officers.
He had criticised staff over the situation, he said.
"There's common ground that various legislative requirements were overlooked. If true, it's a situation we don't need in a highly professional service like ours - and I've told staff as much.
"However, all organisations suffer slip-ups and when things go wrong we don't duck for cover,' he added.
An investigation into the allegations is underway.