Victorian authorities were unprepared for the largest prison riots in the state's history and ignored warning signs of the growing unrest, a report has found.
Inaccurate rumours about a smoking ban and anger that the canteen had run out of tobacco earlier than expected triggered the two-day riot at the Metropolitan Remand Centre at Ravenhall.
Masked inmates armed with sticks smashed windows, bashed doors and lit fires at the maximum security prison, causing more than $10 million worth of damage on June 30 and July 1.
Overcrowding, the rapid rise in inmate numbers and the failure of internal fences and barriers also contributed to the riot which overwhelmed authorities with its sheer scale and intensity, an investigation found.
The number of prisoners being kept at the remand centre increased from about 600 in 2006 to just over 1000 at the end of last year.
With 80 per cent of prisoners being smokers, authorities should have been better prepared, former deputy police commissioner Kieran Walshe said in his report on the riots.
"A smoking ban was going to significantly impact prisoners and this ban should have been met with more regular and robust risk assessments."
Two passive protests were held at MRC the week before the ban was due to take effect.
There had been various reports of growing unrest but despite the earlier identification of significant risks, remand centre staff failed to monitor them.
The MRC should have been in a heightened state of readiness, Mr Walshe said.
If more Emergency Response Group members had been called-in, particularly when the riots first started, the Security and Emergency Services Group could have responded more effectively, the report said.
Corrections Minister Wade Noonan said the government had inherited a system under enormous pressure and the report did not suggest Corrections Victoria should have known a riot of such magnitude would occur.
Mr Noonan said the government would be adopting all 17 recommendations in the riot report and money set aside for upgrading lower security facilities would be re-directed to improving MRC.
The $52 million MRC infrastructure upgrade has already begun, and includes replacing internal wire fences with concrete walls that cannot be pushed over.
The Community and Public Sector Union's Karen Batt said the report highlights that recommendations from previous prison incident reports in 2012 were not fully implemented.
