A lack of suitable accommodation in youth justice facilities run by Child Youth and Family (CYF) has led to almost 700 children and teenagers being held in police cells in the last five years.
Figures provided to RNZ News show the highest number was in 2012 - when 210 people aged under 17 were housed in a cell - but numbers have dropped since then.
Last month in Nelson, two teenage boys spent a total of four nights in a police cell, because there was nowhere else for them to go. One of them, a 15-year-old, was there for three nights over Easter.
CYF's general manager of high needs Nova Salomen said at the time that youth residences had a high turnover and when beds were full, social workers found alternative arrangements in the community.
She said if a person was considered unsafe, they remained in police cells until a secure bed was found.
The Ministry of Social Development was not able to say how many young people in Nelson had been in that situation in recent years, for privacy reasons. It said the figures were low, and releasing the information could make any individuals in question identifiable.
"The need to protect the privacy of these individuals outweighs any public interest in this information," the ministry said in response to the question by RNZ News, requested under the Official Information Act.
However, figures released in response to a Parliamentary question by Green Party MP and social development spokesperson, Jan Logie, showed around the country 686 people aged under 17 had spent time in a police cell in the past five years.
In 2010-11 there were 190, and 210 the following year. But the numbers have dropped since then to 173 in 2012-13, and then 62 and 51 in the two years following.
An ongoing problem
Ms Logie said the numbers did not surprise her.
"This is a problem we've been hearing about for a very long time - that child advocates have been complaining about for a long time because of the harm it causes children being in police cells. So, on that level no, it doesn't surprise me," she said.
CYF said it ran 146 youth justice beds in Auckland, Rotorua, Palmerston North and Christchurch. It did not provide figures on the total number of residential beds around the country.
It said the figures related to young offenders being held in police custody, but in circumstances where police believed the placement offered was unsuitable, they may seek agreement with CYF to hold them in police cells. CYF visited them throughout the period, completing checks on their well-being.
Ms Logie said three incidents in Nelson alone in one month was concerning. She said despite the decline in the number who were housed in police cells, she hoped the incidents in Nelson were an isolated case.
"We're going to have to watch very carefully to make sure those three incidences aren't an indication of a trending up again," she said.
Social Development Minister Anne Tolley attributed the decline to a joint action plan between CYF and Police. Changes included improved information-sharing between the two agencies, improved local transport arrangements and a better out-of-hours response.
Mrs Tolley said the government's focus on reducing and preventing crime and youth crime had led to fewer young people coming into the justice system.
But Ms Logie was not sure the figures told the full story.
"At different times police have put young people in motels, in a supervised situation, which is much preferred to them being in a cell and at risk."
Speaking to Checkpoint with John Campbell, Mrs Tolley said everyone would prefer that young people weren't held in police cells.
While staff at youth residences did their best, they were grim places, she said.
"The work programme that we have rolling out from the CYF overhaul will be addressing exactly that question - what is the most appropriate."
Ms Logie said from conversations with police, they considered the work they did with children and youth was a preventive measure within their youth justice work.
"All of this is around how we as a society are supporting our young people.
"We should have every initiative in place to hold young people who may be a risk to themselves or others, in alternative supervised accommodation, rather than a cell.
Ms Logie planned to seek more information on the matter.
Cells sometimes better than alternative
Daryl Brougham, who has lived in more than 30 foster homes, told Checkpoint with John Campbell there were times he would rather be in a police cell than be in a youth residence.
He said while he was in a youth residence, he was told when to eat and drink and how to think.
"With a police cell... it was a time where I could download, it was a time where I had all the space to myself, it was a time where I wasn't being watched."
He said he believed Mrs Tolley was trying to address the problem.
"I have a great deal of respect for the minister, but I also feel there's a force behind the minister that she doesn't realise.
"And that force is: yes, yes, yes, but, you know, behind the scenes we're going to do our own thing."