An Indigenous teenager has died in hospital one week after he was found unresponsive inside his cell at Casuarina Prison in Perth.
The 16-year-old was found at the Unit 18 youth wing of the adult prison in the early hours of October 12.
Western Australia's Department of Justice confirmed the boy died at Sir Charles Gairdner Hospital just after 10pm on Thursday surrounded by family.
Premier Roger Cook described the teen's death as "heartbreaking and tragic".
"I want to express my sincerest condolences to the teenager's family," he said in a statement.
"My thoughts are with them as they process this difficult time.
"The circumstances surrounding the teenager's death are now subject to a coronial investigation."
Corrective Services Minister Paul Papalia said his thoughts were with the boy's family during the traumatic ordeal.
"The 16-year-old's death is dreadfully sad," Papalia said.
"The Western Australian government is committed to the urgent improvement of Unit 18 - to making it a better place, until we have an alternative location suitable for managing the complex cohort housed there.
"Work to significantly boost the number of staff in Unit 18 is underway and an action plan is being developed to further enhance management of the facility."
Unit 18 was initially established as a temporary facility to accommodate high-risk youth detainees at Casuarina's adult prison.
The state's only youth detention centre, Banksia Hill, also holds juvenile inmates but the cohort was split last year.
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