Concern over prison officer figures
Just 17 prison officers are in charge of more than 3,000 inmates on a typical night shift at open jails, the Prison Officers Association (POA) has said.
The trained prison officers at seven open jails are supported by 26 staff, the POA figures released to the Press Association showed.
POA assistant secretary Joe Simpson said the numbers were "totally inadequate" and added he was surprised that the violent scenes on New Year's Day when inmates went on the rampage at Ford prison near Arundel, West Sussex, had not happened before.
The riot by around 40 inmates, which happened after officers attempted to breathalyse them for contraband alcohol, raised concerns over staffing levels at open prisons after it emerged only two prison officers and four support staff were in charge of almost 500 prisoners on the night shift.
Asked about the figures which showed 43 staff in charge of 3,012 prisoners, Mr Simpson said: "We feel that's totally inadequate to deal with what we've got to deal with during the night."
Inmates at category D open prisons are trusted to go to work in the community, he said. But he added: "Sometimes they come back in at all hours of the night as well. If somebody is working in a hotel in the community they could come back at 11pm."
With the prison night shift often in charge of inmates from 8.45pm to 7am, "the problem with low staffing levels is that, if they've had a drink, they've got to be breathalysed because they're in breach of their licence conditions", he said.
"Prison Service management feel that because it's a category D and low security prison, they only need a minimal level of staffing. But we feel that's totally inadequate to deal with what we've got to deal with during the night. When they're getting drink and drugs, and in some cases women - as it's been reported in the past - it's impossible for the staff who are on duty to cope."
That situation led to the riot at Ford, he said, adding: "I'm surprised this has not happened in the past."
Prisons minister Crispin Blunt said the inquiry into the "unprecedented" violence at Ford would look at the role played by staffing levels.