POLICE have begun their own investigation into events at a young offenders institution which saw prison officers withdraw after coming under a hail of pool balls and an inmate taken to hospital with head injuries.

Specialist riot control officers were called in to quell the disturbance at Deerbolt YOI at Startforth, near Barnard Castle, County Durham, which began on Sunday morning after association – a period when offenders are released from their cells in order to mix.

It was finally brought under control at about 5.50pm, but not before substantial damage had been caused.

Two of the region’s MPs have expressed concern about the situation at Deerbolt, which houses about 500 young offenders aged between 18 and 21.

Darlington MP Jenny Chapman, who is Labour’s spokeswoman on prisons, said: “Incidents like this are of huge concern because they are a threat to staff safety.

“We also know they are becoming more common as our prisons are becoming more and more overcrowded.

“We need to find out what happened here and whether there are any underlying problems [at Deerbolt]. Bringing in reinforcements was the right decision necessary for the safety of everybody involved.”

Bishop Auckland MP Helen Goodman, whose constituency includes Deerbolt, said: “[The] disturbance at Deerbolt is very concerning and reflects concerns that prison staff have been telling me.

“[Nationally] the Government have reduced staffing numbers by the thousands and closed a number of well performing prisons which has increased overcrowding.

“Violence has risen year on year under this Government and serious assaults on staff have increased by 44 per cent since 2010.”

Despite events at the weekend, Deerbolt has been regarded as one of the best performing prisons in the country under the governorship of Gabrielle Lee, who joined in 2012.

It is understood she has now left and a governor from another institution has been placed in temporary charge.

A spokesman for the Prison Service rejected suggestions the incident was in any way connected to what it called a routine staffing change.

He said: “The incident was well managed and there were no injuries to prison staff.”

A spokesman for Durham police said: “This was brought under control by prison staff who did not require police assistance.

“We are deploying crime scene investigators to the site to gather potential evidence and will actively pursue any criminal offences which have been committed.”