The detention of children in watch houses for extended periods, with unaddressed medical or mental health risks, could have "catastrophic consequences", a report has found.
Holding children in watch houses also exposes them to harm and should only be used as a last resort, Queensland's youth detention watchdog says.
The watchdog report into the Cairns and Murgon watch houses in Queensland found youths in the facilities were being held without appropriate access to healthcare.
The report tabled on Wednesday by Queensland's Inspector of Detention Services, Anthony Reilly, made 19 recommendations.
Following inspections of the Cairns watch house in January 2024 and Murgon in November 2023, the report concluded both facilities were inadequate to hold children.
Cairns watch house was overcrowded and had no natural light in its cells or common areas, while at Murgon there was no access to fresh air, the report said.
Both watch houses lacked privacy, with children surrounding themselves with mattresses when using the toilet at both facilities, the report said.
During the inspection, 10 of the 11 children held in Cairns were Aboriginal or Torres Strait Islander.
Murgon watch house held three children - all of them Indigenous.
The inspector raised concerns about the admission processes at both facilities, saying self-harm, suicide risks or significant health issues may not be identified when children are entering.
"This would leave a child, who may subsequently spend many days or even weeks detained in the watch house, with unaddressed risks or medical needs," the report said.
"The consequences could be catastrophic."
In one case study, a child admitted to Cairns watch house staff they had consumed methamphetamine in the 24 hours before their arrest, had a chest infection and had attempted self-harm within the past three months, including while in custody.
No further medical or mental health assessments were undertaken on the day they were admitted, and it was not until the eighth day the child was in custody they were seen by a nurse.
Between January to October 2023, the longest stays at Murgon watch house were two boys aged 14 and 16, who spent 29 days in the facility.
The inspector identified one young person effectively being held in isolation for 12 days because they were the only child at the facility.
Both facilities were inadequate for children but with Queensland's youth detention centres often being full, the report noted it was "likely that children will continue to be detained in watch-houses in the foreseeable future".
"Based on the information in this report, it is clear that the detention of children in watch houses creates the risk of harm and that it should be avoided," the report said.
"If detained in a watch house, children should be held for the minimum time possible, and transferred to a more suitable facility as soon as possible."
Health Minister Shannon Fentiman said the government would adopt the recommendations.
"Watch houses are not the right place for young people," she said.
"Unfortunately, from time to time, they do need to be temporarily detained there until we find them a spot in a youth detention centre."
Two new youth detention centres in Woodford and Cairns are under construction that will almost double the system's capacity.
In August 2023, the Queensland government overrode human rights laws and pushed through amendments to allow children to be held in watch houses.
A Child Death Review report released in March revealed Queensland locked up more children than the rest of the country.
Lifeline 13 11 14
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
13YARN 13 92 76