Prisoner numbers must be cut to prevent further violence, the Parole Board chairman for England and Wales says.
Speaking after a riot at Birmingham prison, Nick Hardwick said there was only "a small window" in which to act.
The Ministry of Justice is recruiting an additional 2,500 prison officers to tackle prison violence.
But Mr Hardwick told the BBC the situation was "very grave" and it would be too long before the extra staff were trained and effective.
Mr Hardwick, formerly Her Majesty's Chief Inspector of Prisons, told BBC Radio 4's The World This Weekend programme that there were widespread fears of violence in the prison system.
HMP Birmingham, where inmates took over four wings and started fires on Friday, had not even been among the institutions causing the most concern, he said.
"The levels of violence and suicide and self-harm are not only increasing, but the rate at which they are increasing is accelerating.
"Successive ministers cannot say that they were not warned about this."
A gold command centre set up by the National Offender Management Service when trouble broke out in Birmingham is still in operation and continuing to monitor any signs of potential disturbance there and elsewhere.
The BBC understands there was a brief disturbance at Hull prison involving a number of inmates transferred from Birmingham, and one wing was in lock-down for up to two hours.
A Ministry of Justice spokesman said: "HMP Hull, like all prisons across the estate, is being closely monitored for signs of potential unrest.
0 comments: