A child detainee who made repeated threats of self-harm was only placed in an "at risk" cell at the Don Dale detention centre after they were found "lying on the floor with strips of clothing around [their] neck", court documents allege.

Key points: Two detainees are pursuing a lawsuit against the NT Government

Two detainees are pursuing a lawsuit against the NT Government Several mental health issues for youth detainees in the NT have been alleged

Several mental health issues for youth detainees in the NT have been alleged Nothing has changed since the royal commission, a youth justice advocate says

The incident, which resulted in the youth being hospitalised, is one of several mental health-related issues raised in an amended statement of claim filed in a civil lawsuit against the Northern Territory Government in the Federal Court on November 20.

The NT Legal Aid Commission, acting on behalf of two detainees, is pursuing the lawsuit against the Government, claiming human rights abuses and racial discrimination continue inside the Territory's youth detention facilities, despite a royal commission handing down a damning report on conditions last year.

In a separate incident, the new documents also allege an Alice Springs detainee who had engaged in repeated acts of self-harm — and whose behaviour was reported to the facility's deputy superintendent in July — was only classified as "at risk" after the child stated they wanted to "end [their] own life" in August.

The documents also claim a detainee with mental health issues — including major depressive disorder, insecure attachment difficulties, and exposure to childhood trauma — was placed in the "back cells" at Don Dale, away from other detainees, and was not "provided with a psychiatrist or any comprehensive plan to support [their] mental health needs".

The Government has declined to comment on the allegations because the case is still before the court, with a trial expected next year.

But its defence papers, filed in September, reject many of the allegations made in the original statement of claim, filed in the same month.

Online questionnaire used to assess mental wellbeing

The latest allegations relate to incidents prior to the November 7 riot at Don Dale, over which eight youths have now been criminally charged.

Sorry, this video has expired Fire engulfed one of the buildings at the Don Dale facility.

The incident was a reflection of the mental state of the detainees, Christine Connors from the Top End Health Service told the ABC.

"It's reflecting obviously that kids are feeling frustrated and feeling agitated — they're feeling anxious and concerned," Dr Connors said.

The Department of Territory Families confirmed that upon entry to an NT youth detention centre, it is a guard who performs an online questionnaire to assess a child's wellbeing.

"The assessment consists of a number of questions to assess risks such as suicide/self-harm, drug and alcohol use, mental health and medical history," a Territory Families spokesperson said.

"The [questionnaire] will determine if the child or young person requires medical or psychological support."

The statement said Territory Families was looking to employ two of its own psychologists to service Don Dale, but recruitment attempts had so far been unsuccessful.

Meanwhile, Dr Connors said the Top End Health Service was responsible for the mental health support for detainees inside Don Dale, and she believed the access was sufficient.

"We employ a psychologist who's got adolescent health experience [and] we've had that position working in the youth detention centre for nearly two years," she said.

Dr Connors said a primary health care nurse with an "expanded scope of care" was also employed at Don Dale to assess and monitor the health of detainees.

She rejected the suggestion that guards were the gatekeepers to children seeking access mental health support.

"They [the guards] need to pass that referral on and then the health centre will work out a time in terms of getting the child to the health centre, which is preferable to do a proper assessment, or if necessary to see the child in their cell," Dr Connors said.

She confirmed that no drug or alcohol rehabilitation was available to youth at the centre.

Guards don't determine whether detainees get mental health support, Dr Connors said. ( ABC News: Tristan Hooft )

Children still kept in isolation: advocate

Darwin-based youth justice advocate Jared Sharp, a lawyer who has provided affidavits in the civil lawsuit, told a rally outside Parliament House on November 16 that children were being denied proper access to mental health support.

"Those boys are locked in their cells for 23 hours per day," he said.

"The Government will tell you they are not being subject to solitary confinement, but you tell me what that is if it's not solitary confinement.

"We had a royal commission, and here we are a year afterwards in pretty much the exact same place as we were before."

Jared Sharp says conditions in B-block are not appropriate. ( ABC News: Mitchell Woolnough )

Mr Sharp rubbished the NT Government's one-year progress report, which he said falsely claimed the reform process was on track.

"I'll tell you about what I see when I go to Don Dale," he said at the rally.

"You see B-block, which when Don Dale was an adult prison was the maximum-security section — and the cells in that section were used for the worst-of-the-worst mass murderers."

He said a girl was being held there in solitary confinement because there was no girls' section at the centre.

He also said 10 Aboriginal boys were being held in the same block.

"They are sometimes let out for an hour a day, but it is with only one or two other boys and it is always within the area of B-block," Mr Sharp said

The Don Dale facility was seriously damaged during a riot in November. ( ABC News: Mitch Woolnough )

Mr Sharp said that one-hour period was the only time the boys could access education or make calls.

"They might have a book if some have been provided by Danila Dilba [an Aboriginal health service], which is pretty much the only humane service in there at the moment," he said.

The ABC reached out to Danila Dilba but it declined an interview.

Conditions better for youth detainees in Alice Springs

The Central Australian Aboriginal Congress provides health care to detainees in Alice Springs, and the CEO said she believed the Government had been implementing "major reforms".

"The priority is to get those current facilities to an acceptable standard," Donna Ah Chee said.

She said what was required was "these centres being locally-based, regionally based, small-scaled and as close to home as possible".

She noted the Government was "only 12 months into the implementation of the [findings of the] royal commission".