Demand and proximity has led to a Palmerston North-based youth justice centre extending its service to troubled teenage girls.

The Te Au Rere residence, established for young male offenders, has began accepting females.

Since May 20, 29 young female offenders have been placed there.

General manager residential and high needs services for Child, Youth and Family Nova Salomen said while Te Au Rere was considered an all-male centre, girls had previously been placed there on an ad hoc basis.

Te Au Rere provides safe and secure residential care for people aged between 14 and 17.

Salomen said part of the reason to relocate girls to Palmerston North was because the majority of girls needing to be in a secure residence were from the middle of the North Island and below.

Of the 29 girls taken in during the past five months, 13 were from Auckland, one was from the South Island and the remaining girls were from elsewhere in the North Island.

Te Au Rere had a policy of residential availability which was flexible around gender allocation of beds when the need arises, Salomen said.

Gender allocation over time was monitored and modified according to demand and trends.

The centre's units were single-sex, however some classes and activities had a mix of males and females, depending on a young person's individual needs. Staff fully monitored these interactions, Salomen said.

Since the addition of female residents, the staffing levels at Te Au Rere had been maintained at two-and-a-half to three staff members per young person, to keep both residents and staff safe, Salomen said.

The 2014 Child, Youth and Family residential care regulations inspection report stated about 90 full-time permanent staff work at the residence.

Peter Butler, general manager of youth service Start, said he thought the facility could be including females for locality reasons.

"They try to keep them as based as possible to the local community so that there are family around," he said.

City councillor Aleisha Rutherford said the decision to add female youth to the facility would have little impact on the Palmerston North community.

Rutherford was a part of the community liaison committee at the justice facility about four years ago.

The facility was a justice option for young people under 17 who had committed a range of offences, from minor offences including theft, to major crimes including manslaughter and murder, Rutherford said.

She said she believed including young women at the Te Au Rere facility had been in the pipeline for years, and was finally possible following a building upgrade in 2012.

The upgrade incorporated smaller, 10-person units to the centre which has a 30-person limit.

The centre placed focus on reducing reoffending numbers and making sure youths had "really good family and whanau support," she said.

Te Au Rere is one of four youth justice secure residences in New Zealand. The other three are Korowai Manaaki, in Auckland, Te Maioha o Parekarangi in Rotorua and Te Puna Wai o Tuhinapo, in Christchurch.

*An earlier version of this story said Aleisha Rutherford had worked at the facility. This was incorrect.