The girl is just 12 years old and has been in the Brisbane City watch house for nine days so far.

Key points: Nearly half the children in the youth justice system are under a child protection order

Nearly half the children in the youth justice system are under a child protection order Children aged between 10 and 17 are held in adult watch houses because no youth detention centres are available

Children aged between 10 and 17 are held in adult watch houses because no youth detention centres are available The Office of the Public Guardian deals with reports of isolation, attempted suicide and children with cognitive impairments who have been detained

The Office of the Public Guardian is "extremely concerned about her wellbeing" and is trying desperately to get her shifted out of the maximum security adult facility and into a more suitable youth detention centre.

"I can't imagine what these kids are experiencing when they're in full view of adults having all sorts of episodes, coming down off drugs, listening to the screaming. Some of these kids might be 12 years old but some of them are operating at the capacity of a six-year-old," Queensland's Public Guardian Natalie Siegel-Brown said.

An official from the Department of Youth Safety writes back to the Public Guardian, confirming the girl has spent the entire nine days at the watch house "in an observation cell (on her own) in a suicide gown".

"That's for their own safety," Chief Superintendent Cameron Harsley said.

Chief Superintendent Harsley is in charge of the state's 63 watch houses.

"A smock is very similar to a hospital smock. It is designed so you can't hang yourself or harm yourself with it," he said.

The 12-year-old is subject to a child protection order.

Most often children placed under these orders have been removed from their parents because of abuse and neglect.

Nearly half the children in the youth justice system are under these orders. In 2017-18 the Children's Court reported "771 distinct young persons spent at least one night in a police watch house".

Visitors from the Public Guardian's office report that the young girl is asking to wash her hair.

She's complaining that it's "very untidy and knotted" because she has been in the watch house for more than a week without any shampoo.

Queensland's Public Guardian Natalie Siegel-Brown says the children held in adult watch houses are not hardened criminals. ( ABC News )

'They are victims of child abuse and neglect'

While this vulnerable young girl is the "highest on the priority list" to be shifted out, there is no bed at the youth detention centre for her — so she's staying at the watch house.

The girl is one of hundreds of children, aged between 10 and 17, who are being held in adult watch houses in Queensland every year, because there are no youth detention centre beds available.

And she is just one of hundreds of cases contained in reports and correspondence from the Public Guardian's office obtained under Right to Information.

The reports often deal with serious incidents inside Queensland's watch houses, including the use of isolation, kids attempting suicide, and children with cognitive impairments being locked up.

In one case, it was discovered a 16-year-old in the Brisbane watch house was pregnant.

It took almost a week to find her a bed elsewhere and shift her out.

"At the end of the day, this is a concrete pen, designed to hold adults in an acute and dangerous state for up to 48 hours," Ms Siegel-Brown said.

One of the roles of the independent office of the Public Guardian is to monitor and advocate for the rights of every single child in the child protection system, including the growing numbers now held inside the Brisbane City watch house.

Children as young as 12 have been placed in isolation cells and suicide gowns. ( ABC News )

Over the last 18 months, Ms Siegel-Brown has seen the numbers of children being held in the state's watch houses surge, because there is no more room at Queensland's two youth detention centres.

She argues that despite some portrayals, most of the children who end up in watch houses are not hardened criminals or serious offenders.

"These kids get labelled as crims by mainstream society, but I can tell you that they are in there for the most minor of crimes.

"The important thing to note is that the vast majority of them have never actually been convicted. They are victims of serious child abuse and neglect, physical neglect, emotional neglect. They've never felt safe in the environment they've grown up in. They've never felt loved."

Queensland's Child Safety, Youth and Women Minister, Di Farmer, told Four Corners that while watch houses were "not an environment, obviously that is good for young people", there are often no other options.

"If the magistrate has ordered for them to be in the watch house and we cannot, we do not have any space in the detention centre, then there is no alternative for them."

The case of the 12-year-old girl highlights the use of observation or isolation cells in the Brisbane watch house, and the holding of children in so-called "suicide smocks".

"For example, one young lady said she was held down by several officers and stripped to be put in a suicide smock in full view of male officers," Ms Siegel-Brown said.

"Until very recently the children were not permitted to wear underwear under their suicide smock. On the basis that the underwear might also be used to attempt or succeed at committing suicide. And it's only been with a great deal of advocacy from my office that the children and young people are now allowed to wear underwear under the suicide smock."

Chief Superintendent Cameron Harsley is in charge of the state's 63 watch houses. ( ABC News )

Ms Farmer said the decision to place a child in a suicide smock was to minimise harm.

"Well I have to take the advice of the police that that is the thing that is going to minimise harm. So that's their advice, and they, you know, they're quite unequivocal about that," she said.

Padded cells and suicide smocks are 'for their own safety'

The Office of the Public Guardian said there have been about three suicide attempts inside the Brisbane City watch house by children and juveniles in recent times.

"Yeah, we've had young people in the watch house that have tried to commit suicide," Chief Superintendent Harsley said.

"We've intervened on each occasion. We've either removed them to an isolation cell or more likely than not, we take them to a mental health facility up at the hospital and get them assessed for their wellbeing."

Chief Superintendent Harsley said children who are deemed at-risk, or who threaten self-harm, are placed in padded isolation cells and placed in a smock for their own safety.

But the Public Guardian said the use of isolation on children was "dehumanising".

Nearly half the children in the youth justice system are under child protection orders and have been removed from their parents due to abuse and neglect. ( ABC News )

"My understanding from my reports that there was a young man held in an isolation cell for 23 days. When my staff or myself speak to children in those isolation cells, you must speak to them through a slot that is only yea big. I had to kneel on the ground to peer through, to be able to communicate with a young person. What's that doing for a child?"

Ms Farmer said she was unaware of the case of the boy held in isolation for 23 days.

But Four Corners has seen a complaint about the case sent to her department by the Office of the Public Guardian earlier this year.

Chief Superintendent Harsley said his staff are also feeling the strain of having to deal with children and juveniles in watch houses.

"When they're dealing with youth, they sometimes self-select that they don't wish to deal with the youth in custody, which we observe that and remove them from that environment, because it can be distressing for them having to deal with children in a watch house. I respect that. It's not for everyone, and we move them out to other duties."

The 12-year-old girl was eventually moved to a youth detention centre.

Watch Mark Willacy's investigation, Inside the Watch House, on iview.