AN outbreak of violent disorder that left two wings of HMP Erlestoke closed for a year cost the taxpayer more than £1m.

The incident, which took place in June last year, resulted in 130 prisoners being shipped out from the Wiltshire prison.

At the time, the Ministry of Justice denied it was a riot and said that "some minor structural damage" had been caused.

But the eye-watering repair bill revealed in a new report suggests that the full scale of the disorder was worse than acknowledged.

The cost of repairing the two wings - Alfred and Wessex - came to £800,000 while the installation of new cell doors, hinges and observation panels will cost another £300,000.

It is hoped that prisoners will not be able to smash their way through the new doors as they did during the violence last year.

The Prison Officer's Association (POA) has previously accused the Ministry of Justice of seeking to downplay the seriousness of the incident.

POA spokesman for the South West and Wales, Mark Fairhurst, said: "They are trying to say it was not a riot and only three people were involved which is ridiculous.

"I have spoken to officers who were on duty and I have been told that while the situation started with three people kicking through the wooden doors of their cells it quickly escalated with other prisoners smashing up their cells."

In the week leading up to the incident there had been a roof top protest and a number of violent assaults both between prisoners and between prisoners and officers.

"Our members had been very worried about a lack of staff," added Mark. "They were scared something was going to happen."

The fears of POA members are echoed in the new report which finds that the lack of staff meant prisoners were being kept locked in their cells for far longer than normal which in turn was causing tension and frustration to build.

On the day that the pressure cooker environment on the wings finally blew there were only 15 prison officers, compared to around 500 prisoners, on duty to contain it.

Squads of specially trained Prison Service riot officers - known as tornado teams - had to be drafted in to help regain control.

The report praised the dedication shown by a number of officers during the incident.

But it also found that the causes were not limited to conditions at Erlestoke alone.

The prison's Independent Monitoring Board believes that the mis-categorisation of higher risk prisoners was a contributing factor.

Erlestoke is a category C prison but a number of category B prisoners from elsewhere in the country had been sent there in error in the run up to the incident.

The use of smart phones smuggled into the prison was also found to have enabled prisoners to communicate during violent incidents.

The Prison Service says time has now been found for routine and intelligence-led searching of all staff and visitors coming into and out of the prison. Out of hours cell searching has also led to a high number of phones being discovered.