Justice Secretary Chris Grayling is under fresh pressure to explain how a riot broke out a North East prison after his version of events was publicly questioned by a prisoner there.
A stand-off between prisoner and officers at HMP Northumberland, in Acklington, in March, saw around 50 inmates take over a wing at the jail on March 29 this year.
When the Justice Minister visited the jail a month later, he said there was disorder because prisoners were forced to work longer days and “didn’t like it”.
But an inmate has written to prisoners’ magazine Inside Time to claim the Minister is attempting to make a “cover up” and that the riot was down to frustration at staff shortages which had put a stop to some workshops.
The Ministry of Justice denies any working hours have decreased and stressed it will ensure the prison has “enough staff to a deliver safe and effective prison estate.”
But representatives of probation staff say they are concerned at problems at the jail since it was privatised while local MP Sir Alan Beith is also seeking answers.
The row comes after talks began last year on plans to cut 200 jobs at the prison - run by private firm Sodexo - which houses more than 1,300 inmates.
The inmate wrote in Inside Time: “I am writing in respect of the visit here on April 11 by Justice Secretary Chris Grayling after 50 prisoners took over Houseblock 4.
“Apparently Mr Grayling told local media that the mutiny was over prisoners being upset because they had to work longer hours. This is an absolute cover-up, there is no work here.”
He added: “The real reasons for the riot (and let’s remember that no prisoner will riot without very good reason as it can mean an extra 10 years added to their sentence) was about the changes that Grayling has forced on the prison system.”
Another inmate at the prison has also written to Inside Time, saying: “I am not surprised by the recent riots on Houseblock 4 and I would not be in the least surprised if there are more riots here.
“The main problem is the lack of work. There are over 1,300 prisoners here but only around 700 jobs. This means that nearly half the population are not working and locked in their cells for 22 hours per day.”
Berwick MP Sir Alan Beith has raised concerns about staffing at the jail.
He said: “I have raised concerns about staffing numbers at the prison with both Sodexo and the prisons minister and I am continuing to pursue this and other issues. None of these concerns, - important as they are - are any excuse for prisoner disorder which poses dangers to staff and to other prisoners.”
Mike Quinn, a regional representative for the probation service union NAPO, said: “The letter recently published in Inside Time gives us a small insight into the deterioration in conditions at HMP Northumberland since its privatisation.
“Our members will become very concerned about the ability of the prison to carry out any meaningful work with prisoners whilst in their custody.
“The importance of having meaningful and purposeful activity to undertake whilst in custody can not be underestimated, particularly work to reduce the risk of harm prisoners will pose when released.
“If this disastrous example of privatisation within the criminal justice system is a sign of things to come then the public should be concerned.”
A Prison Service spokesperson said: “It is totally wrong to say that prisoners at HMP Northumberland do not have access to work - in fact the overwhelming majority currently have jobs which assist in their rehabilitation, as well as access to a range of education opportunities.
“There is also a library service available in the prison with all prisoners having access to books.
“Staffing levels across the estate are strictly risk-assessed and we will always ensure that there are enough staff to a deliver safe and effective prison estate.”
Recently published Government figures showed that the prison had an average of just eight spare spaces each night between January and April, meaning it was running at 99.4% capacity.