The WA government is facing renewed criticism of their justice system after Premier Roger Cook called a youth unit inside an adult prison a "necessary evil".

Mr Cook's comments came during a media conference after a 16-year-old Aboriginal boy was found unresponsive in his cell at Casuarina prison's Unit 18 around 2:00am on Thursday.

The boy is understood to have attempted suicide.

He was quickly rushed to Perth's Sir Charles Gairdner Hospital after he was observed by officers conducting routine overnight checks where resuscitation commenced.

The boy is said to be in a stable but critical condition.

"This is an incredibly sad situation and we're all very distressed about it," Mr Cook said.

Unit 18 has been central to concerns, alongside Banksia Hill Detention Centre, around WA's youth justice system after it opened as to house young people within the otherwise adult prison last year.

According to reports, Mr Cook conceded Unit 18 did not meet care and safety standards but described it as a "necessary evil" as the state works to make changes to the system.

National Suicide Prevention and Trauma Recovery Project director Megan Krakouer told National Indigenous Times the comments were "disgraceful and harmful", "showed a lack of understanding", "disconnect" and "ignorance of the operations of Banksia Hill and Unit 18".

"Mr Cook should really know better," Ms Krakouer said.

She said it poses the question to whether Mr Cook has seen the conditions in Unit 18 for himself or only heard second-hand descriptions.

Ms Krakouer called for the resignation of WA Attorney General John Quigley and WA Corrective Services Commissioner Christine Ginbey.

"Under their leadership, nothing has changed," she said.

"We're now in a hospital in another awful predicament because of their failure."

The office of Corrective Services have contacted the family of the boy to offer a level of support.

Ms Krakouer has accompanied the boy's family at hospital and in the time since.

According to the ABC, Corrective Services Minister Paul Papalia had attributed the number of suicide attempts at Unit 18 to the affected "cohort" of children rather than conditions within.

Dana Levitt, who is leading a class action of behalf of Unit 18 detainees against the Government said the boy has been "deteriorating significantly" since being moved from Banksia Hill since May.

She told the ABC the government has continued "to peddle this policy of containment".

Reported figures have also presented to show the majority of detainees at Unit 18 spent less than two hours on average outside of their cells through September.

At Banksia Hill, the same period showed an average of over nine hours out of cell.