Two separate investigations will be held into the New Year's Day riot at Ford open prison where balaclava-clad inmates torched buildings in protest at a clampdown on illegal drinking.
The prisons minister, Crispin Blunt, confirmed today there would be an internal Prison Service inquiry and a police inquiry into the violence, which is estimated to have caused about £3m damage.
Twenty-three inmates have been dispersed to secure prisons across the country after accommodation blocks, a gymnasium, a mail room and recreation room with 10 newly installed pool tables were destroyed in the blaze.
The disturbances began in the early hours of New Year's Day after staff attempted to test prisoners for alcohol consumption. Around 40 inmates - many disguised in balaclavas - are believed to have taken part in the rampage.
The prison, near Arundel, in West Sussex, was brought back under control at 10pm yesterday after riot control officers were sent in to protect the fire brigade as they extinguished the flames.
Speaking on Sky News, Blunt said the police inquiry could lead to criminal prosecutions as well as administrative punishments such as loss of sentence reductions for inmates. The minister described the destruction as "unprecedented" and promised lessons would be learned to ensure there would be no repetition of the violence. He declined to comment on reports there were inadequate numbers of staff on duty on New Year's Eve.
Open prisons hold inmates nearing the end of their sentences prior to release and low-risk prisoners serving shorter jail terms. The Prison Officers Association claimed that as few as two prison officers and four support staff were present at the time to manage a population of almost 500 inmates in Ford.
Yesterday Michael Spurr, chief executive of the National Offender Management Service, said the staffing levels were considered appropriate and played down the extent of the damage.
He said: "Although damage has been sustained to the prison, there has only been a minimal loss of accommodation. These types of incidents in open prisons are rare and it is to the credit of all the staff involved that no staff or prisoners sustained significant injuries
"Staffing levels at the prison at the time the incident began were risk-assessed and considered appropriate and usual for an open establishment such as Ford. A high-level investigation will commence immediately to ascertain the causes and circumstances surrounding the incident and those involved may be liable to criminal charges."
Mark Freeman, deputy general secretary of the Prison Officers' Association, said alcohol had been a concern at the jail for some time, with dozens of empty bottles found in recent days.
"In the early hours, staff tried to breathalyse a number of prisoners because they suspected they had been drinking," Freeman said. "A total of 40 bottles of alcohol have been found empty. It's been a concern here for a long time about the amount of alcohol prisoners are able to get. When the prisoners refused to be breathalysed they became violent along with other prisoners and went on what we call a mutiny."
He added: "This has been a long time waiting to happen. Staff have been running around trying to breathalyse prisoners. It's been reminiscent of the end scenes of The Benny Hill Show - the only thing missing was the music. It's very difficult when you have a very small staff …
"In our view they do not have enough staff. The general policy is that prisons in an open state have less staff but we feel they should have more because they have more access to illegal activities. This is what happens when you have the mix of easily available alcohol and the wrong type of prisoner."
Freeman said six prisoners had been identified as the ringleaders. Three of these were being transferred to another jail. He said the other three were "hiding" among the other prisoners.
Juliet Lyon, director of the Prison Reform Trust, said: "No one wins from a prison disturbance. It endangers prisoners and staff, worries families and ends in a high cost the Prison Service can ill afford. Once control is fully re-established, a review is called for to determine how and why this happened. Events of this kind are very rare in open prisons, which serve an important purpose to rehabilitate people who have served ever lengthening sentences."
The Prison Service internal inquiry will be led by the regional custody manager for Wales.
HMP Ford is a former naval air base. It houses category D prisoners, those deemed by the authorities to be trusted not to escape and as such allowed to reside in an open prison. Among past high-profile inmates were George Best - who played football for the prison team while serving time in 1984 for drink-driving offences –the renegade spy David Shayler, as well as Ernest Saunders, Anthony Parnes and Gerald Ronson, three of the so-called Guinness Four share-trade fraudsters.