Australian prison
Questions are being asked of why the maximum security prisoner, with radical Islamist sympathies, was housed with a minimum security cellmateGetty

A teenage prisoner in Australia, who supports the jihadi group Islamic State (Isis), has sent his cellmate to hospital after carving an IS slogan into his forehead, in what prison officials have called an act "not unlike torture".

The 18-year-old petty criminal, who was named by the BBC as Bourhan Hraichie, carved the slogan "e4e" (eye for an eye) into his 40-year-old cellmate's head using what has been described as "a sharp tool".

While Hraichie was not arrested for terror-related activities, questions are now being asked why the maximum security prisoner, with radical Islamist sympathies, was housed with a minimum security cellmate. The grisly attack took place at the Mid North Coast Correctional Centre in Kempsey, south eastern Australia.

The Chairman of the Prison Officer's Branch of the Public Services Union told The Sydney Morning Herald the two men should never have been placed in a cell together.

"It was a complete failure by the people in positions of responsibility, who had access to that information, to share it with the people who needed it to do their job," Steve McMahon was quoted as saying.

"It's quite a horrendous piece of work, not unlike torture," he added, explaining the prison service need to do more to address a growing problem of radicalised inmates in Australian jails.

New South Wales Minister for Corrections David Elliott called placing Hraichie in the cell with the older man "a stuff-up".

The head of the correctional centre where the attack took place has been suspended while an inquiry is under way to understand how and why the high-risk offender was able to carry out the attack.