SYDNEY - The Australian government ordered an inquiry today after graphic evidence emerged of prison guards assaulting and tear-gassing teenage boys, with one shown hooded and shackled to a restraining chair.

Prime Minister Malcolm Turnbull said he was "appalled" by the images aired by the national broadcaster ABC from a youth detention centre in the Northern Territory.

"Like all Australians, I’ve been deeply shocked -- shocked and appalled by the images of mistreatment of children at the Don Dale Centre," he said.

"We will be establishing a Royal Commission in to these events, into this centre. We intend to do so jointly with the Northern Territory government.

"This needs a thorough inquiry, we need to move quickly on that, get to the bottom of it and expose what occurred and expose the culture that allowed it to occur and allowed it to remain unrevealed for so long."

The ABC’s Four Corners current affairs programme on Monday night showed footage of offenders, many indigenous, being stripped naked, tear-gassed and held in solitary confinement for weeks at the centre in 2014 and 2015.

In one video, a 17-year-old is hooded, shackled to a restraint chair by his ankles, wrists and neck and left alone for two hours.

The Northern Territory has one of the highest crime rates in Australia, with indigenous offenders making up more than two-thirds of the prison population.

According to Amnesty International, Aboriginal children are 26 times more likely to be jailed than their non-indigenous counterparts as they struggle to deal with poor education, high unemployment rates, and substance abuse.

Northern Territory Chief Minister Adam Giles said he was "disgusted" by the revelations, but added he had "full confidence in the majority of custodial officers" working in such institutions.

Human Rights Watch said it had long been urging the government to act on abuses in juvenile detention, and that the Northern Territory issues were just the tip of the iceberg.

Its Australia director Elaine Pearson said what happened at the Don Dale Centre was "a classic example of how not to deal with troubled youth".

"Excessive use of force, isolation and shackling of children is barbaric and inhumane," she said.

"This is not only a matter of training. Excessive force is an abuse and the perpetrators of such abuses should be held to account.

"Better alternatives to locking kids up for prolonged periods must be found," she added.

Save the Children said the inquiry needed to be Australia-wide and not just into the Northern Territory.

"This reprehensible and outrageous behaviour does nothing to help rehabilitate youth offenders who should be supported to prevent them from offending again," said spokesman Mat Tinkler.

"The solution to preventing future abuses is not to lock up children in the first place." - AFP