The potentially deadly "folding up" restraint position used in Western Australia's youth detention system will be banned within weeks after a public outcry against the practice.

Last month The West Australian and ABC's Four Corners published footage from within Banksia Hill Detention Centre showing prison guards using the notorious restraint on a 14-year-old boy earlier this year.

The restraint involves guards forcing a handcuffed child onto their stomach, crossing their legs behind them and sitting on them.

At the time WA Premier Mark McGowan and corrective services minister Bill Johnston said they had been unaware of the use of the restraint, which has been banned in Queensland because of the asphyxiation risk it poses, and Mr McGowan said the practice would be reviewed.

The security footage captured the boy crying out that he couldn't breathe when held in the restraint.

It is understood that he had attempted to hit a guard with a mop after a prolonged period locked in his cell.

On Thursday Western Australia's Department of Justice confirmed the review of the "folding up" restraint was complete and "an alternative method of restraint for youth detainees to replace the figure four technique" had been selected.

"Training for youth custodial officers in the alternative technique will begin on December 5… Use of the figure four technique will be phased out from that date and will cease by December 14," it said in a statement.