A South Auckland community is fighting plans to transform a Manurewa children's care facility into youth prison, saying it will put neighbouring families and children at risk.

The Whakatakapokai care facility in Weymouth currently houses up to 20 young people who are being looked after by Oranga Tamariki.

But with the age at which young people are dealt with by the youth court rising to 17 in July, plans are underway to have the facility repurposed to accommodate an increase in young offenders.

It sounds like a classic case of "not in our backyard" - but those in the area are challenging any other neighbourhood to deal with a prison over their fence - let alone three others within 4km.

Dene Andre has been living in Manurewa for most of his life and said the area was the prison capital of New Zealand.

"We're the only suburb or town in the whole of New Zealand that has three prisons - as far as I know, no one else has more than one prison in the area - now they want to put a fourth one in and I just personally think that that's just totally unjust," he said.

Oranga Tamariki sent letters to Weymouth residents in January, informing them that they would be changing the facility's focus from only care and protection, to include youth justice.

The change would also see the number of people housed at Whakatakapokai increase from 20 to 30.

Mr Andre said that would essentially make it another prison.

"All the social services in Manurewa are under stress, and the people are under stress, and all those people who come and visit people in prisons, where do they stay?

"They stay in Manurewa - they bring their problems and their difficulties and their struggles with them - and the community has to interact with all of those things on a daily basis, and another prison in the area is only going to make that worse," he said.

Three of Whakatakapokai's boundaries back onto residential houses and a public park with a children's playground.

One of those homes belongs to Lily Li and her husband Bruce Chen.

Ms Li said when they first bought their house they thought the care and protection facility was a good thing, to help vulnerable children - but she was totally opposed to offenders living there.

"Not a youth justice prison. No way," she said.

Darcelle Bell Ata-Ata is another Weymouth resident opposed to the change - she lives down the road with her husband and three children and is worried about escapees.

"It's that fear of, what are we dealing with? Also the calibre of offender - are these car thieves? Do they have some serious aggressive behaviours?"

She acknowledged the kids that Oranga Tamariki would be taking in did need proper care - but said Weymouth wasn't the appropriate place.

"We already deal with high levels of car theft and car tampering by youth in this development," she said.

Mr Andre said Whakatakapokai was used to house youth offenders in the past, but that ended in 2002 and it has since only been used to accommodate young people needing care and protection.

"We experienced a lot of burglaries, car thefts and other trouble in the 1990s and the government acknowledged that and moved them to Korowai Manaaki," he said.

Off to court

Oranga Tamariki is headed to the Environment Court this month to have the case for repurposing the site considered.

Because of that court action Oranga Tamariki wouldn't comment on this case, but in a statement deputy chief executive of Youth Justice Services Allan Boreham said Youth Justice residences provided a safe, secure and supportive environment where young people can get their lives back on track.

He said children and young people benefited from being accepted within their own community and feeling like they had a place to belong.

Mr Andre said the community won't take the change lying down - more than 100 residents have made submissions to Auckland Council in opposition, and several will be appearing before the Environment Court.

"They say 'you're a NIMBY because you don't want a prison in your backyard', well I'm sorry, we've got three prisons already - when is enough, enough?"