A review into youths detained in police cells should ring alarm bells on how children are being treated in the judicial system, says UNICEF NZ (UN Children's Fund).
The report, released by the Independent Police Conduct Authority, the Human Rights Commission and the Children's Commissioner, has been broadly welcomed, but the children's advocate said real changes needed to be made immediately before a dent was made in youth offending.
UNICEF NZ's national advocacy manager Barbara Lambourn said they had known for many years that steering children away from further delinquency, anti-social behaviour and criminality depended on how they are treated in the early stages of their offending.
"...locking children up should always be a last resort and that more attention needs to be paid to the rights of the child in such situations."
The Chief Youth Court Judge Andrew Becroft said the report was "timely and very helpful".
"It's a reminder that we need to do better. Certainly in recent years there has been a creep towards more use of police cell remands - mind you it's not nearly as bad as it was in the mid-2000s."
Most police cells were built for adults, he said.
"For a young person it would inevitably be solitary confinement...visitation rights by families are hard, sanitation, meals, shower facilities are problematic and we know that it is a high-risk environment for teenagers."
He said the teenage brain, which was a "work in progress" was particularly susceptible to periods of solitary confinement which could not be predicted.
Labour's police spokesman Kris Faafoi said the review highlighted that police needed further training in dealing with youths.
"Because they are children I think (the report's) recommendations should be heeded because there's a situation with young people where we want to prevent further crimes and further victims."
Green Party co-leader Metiria Turia said realistic bail options needed to be offered to youths.
"Locking up a young person in a dirty cell doesn't 'teach them a lesson', it makes them angry.
"Abusing young people's rights and treating them badly sets them up to resent authority and makes it more likely they will reoffend because they have been given no reason to respect police," she said.
The party backed many of the recommendations, including properly resourcing Supported Bail programmes so that youths could stay with family or an approved caregiver, she said.
Police Minister Anne Tolley said she would be discussing the review with police.
"This is a timely report and I'm satisfied that it contains recommendations which the police are already addressing," she said.
"The crime prevention focus, and alternate resolutions, will help to keep young people out of the criminal justice system - while improvements are being made including staff training for police officers and closer relationships with Iwi and community groups."
Assistance Police Commissioner Nick Perry said policing young people brought "unique challenges", but they were committed to trying to reduce the number of youths held in cells.
"Policing of children and young people is one of our five key focus areas. It is where prevention of crime starts so we are very mindful of the need to get it right," he said.
Mr Perry said the review into detaining youths found that while detention was sometimes necessary, it could be a missed opportunity for a more constructive response to a young person's offending.