It is extraordinary that a West Auckland teenager was held in police station cells for four days because Child, Youth and Family could not find a bed for her, Labour says.
The teenager was "terrified" listening to other prisoners scream through the night, and tried not to eat or drink so she did not have to use the toilet in front of anyone.
A bed was eventually found for her in a youth justice facility " in Palmerston North.
Jacinda Ardern, Labour's spokeswoman for children, said the problem of capacity at residences was not new, and what had happened to the young woman was unacceptable. "To have a young person kept in that situation for four days is unacceptable, and just should not have happened in the first place. Police cells are not designed to hold adults for long periods of time, let alone children.
"To learn that they don't have available beds for young women, it seems extraordinary, given it is well known in the sector that there is a growing number of girls falling into the category of needing to come into care and protection because of criminal behaviour."
Waitakere police inspector Rod Fraser said every effort was made to ensure youths who had to be held in cells were "as comfortable as possible and that they have a placement with CYF as soon as practicable".