Youths in Queensland detention centres have had bones fractured by restraints, been humiliated in strip searches and have been put in solitary confinement, newly obtained documents reveal.
Amnesty International got the official documents through a Freedom of Information Act request. In one case a boy was held down on the floor by a group of guards, and had both his hands and legs cuffed.
The boy had been identified as being a high suicide risk. After being cuffed, he was locked in a "tiny" isolation cell where his clothing was cut from him with a knife.
He was left naked in the cell for more than an hour before being given a gown to wear. The incident happened at the Cleveland Youth Detention Centre (CYDC) in 2013.
Other documented incidents include:
Amnesty International is calling for independent investigations into child abuse at all Australian detention facilities.
The organisation says indigenous Australians make up a majority of detainees in the centres.
"These official documents shine a light in the darkest corners of these detention centres, and reveal incidents, and in some case policies, which may constitute cruel, inhuman or degrading treatment or punishment, in violation of Australia's obligations under international law," said Champa Patel, Amnesty International's senior research adviser for southeast Asia and the Pacific.
The shocking new details of abuse come after video emerged showing young people being mistreated at a Darwin detention centre in July.
It showed one teenager, 17-year-old Dylan Voller, strapped to a restraint chair with his head covered. It also included footage of him being stripped, assaulted and mistreated. He was one of six children tear-gassed at the detention centre in 2014.
The footage was shown on ABC's Four Corners programme at the former Don Dale detention facility in Berrimah, outside Darwin.
Also recently, more than 2000 incident reports were leaked describing sexual assault and self-harm - mostly involving children in the asylum seekers' detention centre on Nauru.