An Australian prisoner who supports the so-called Islamic State has allegedly used a knife to carve a slogan on to his cellmate’s head.
Reports said the Islamic State mantra “e4e”, standing for “an eye for an eye”, was carved into man’s head.
An inquiry will examine how the high-risk attacker, 18, came to be housed with his 40-year-old cellmate.
New South Wales Corrections Minister David Elliot said placing the pair in the same cell was “a stuff-up”.
The attack took place at the Mid North Coast Correctional Centre in Kempsey, 4.5 hours north of Sydney.
The injured man was a minimum-security prisoner and the teen, named by multiple sources as Bourhan Hraichie, was a maximum-security prisoner, reports said.
Initial reports said the injured man had served in the Australian army in East Timor, but Mr Elliott said he did not believe this was accurate.
“It is important to note that the man’s background does not change the seriousness of this incident,” Mr Elliott said in a statement to the BBC.
The general manager of the Mid North Coast Correctional Centre has been suspended while an investigation takes place.
Head of the Prison Officer’s branch of the Public Services Union Steve McMahon told the media prison officers were distressed by the allegedly unprovoked attack, which took place on Thursday.
“It’s quite a horrendous piece of work, not unlike torture,” Mr McMahon reportedly said.
He said the pair should never have been placed in the same cell and described the incident as a “complete failure by the people in positions of responsibility”.
The 40-year-old man was admitted to Port Macquarie Base Hospital in a critical condition, but was now stable, a hospital spokesperson told the BBC.
Police have charged Hraichie with causing grievous bodily harm with intent and intentionally choking a person.
He has been ordered to face court on May 23.