Principal Youth Court Judge John Walker says the number of teenage offenders forced to spend the night in police cells is unacceptable, as they're no place for young people to spend the night.
Figures acquired by RNZ show young offenders spent at least 24 hours in police cells on 151 occasions from June 2015 to 2016 - an increase of nearly 200 percent on the previous year.
Teenagers between 14 and 16-years-old can be remanded in police custody if Child, Youth and Family can't provide a bed for them at a youth justice residence, however it is meant to be a "last resort option".
Judge Walker said the figures were unacceptable.
"Three, four, five days of a young person in police cells does happen... It's unacceptable. One night is bad enough, more than one night is unacceptable."
Nelson lawyer John Sandston said the practice had no place in a first-world country.
He said he had dealt with a case where a teenager was in the Nelson police station for about four days in December.
"It's ludicrous because this problem has been going on for many years."
In a statement, Child Youth and Family acknowledged youths spending nights in police cells was not an ideal situation.
"We are aware of the judges' concerns about placing young people in cells... every effort is made to avoid this situation."
"One issue which is impacting bed availability is the heavy use of youth justice residences for young people who are remanded in custody. We are working with police, the courts and the community to find suitable alternatives to remands in custody."