INMATES armed with pool cues and pieces of furniture threw snooker balls at prison officers and ripped apart a recreation room at a young offenders' institution.

Two inmates were hurt as 26 youths became involved in the riot, before barricading themselves in a common room.

It is the second time in four months that police and other outside bodies have been called to Deerbolt Young Offenders' Institute, in Startforth, Barnard Castle, County Durham, to break up major incidents involving violence.

No one knows what started the riot in D Wing on Wednesday, but prison officials confirmed there had been a dispute between an inmate and an officer over a locker search earlier in the day.

The violence broke out at about 7.20pm and it took prison officers, police and firefighters about three hours to bring the situation under control.

Pool tables and furniture were smashed, windows were shattered and fire fighting equipment was broken.

The dining room, recreation room and nearby offices were severely damaged.

One inmate was treated in hospital for scalding injuries, before being taken back to the institution early yesterday.

It is believed that seven or eight inmates have been removed from the institution and placed elsewhere.

A prison service spokesman said: "Prison staff contained the incident and managed the voluntary evacuation of the prisoners by 11.30pm.

"No staff were injured. One prisoner was treated in the prison hospital for a pre-existing knee injury, which was knocked during the fracas.

"Another prisoner was briefly treated in an outside accident and emergency hospital for scalding before returning to the prison.''

The violence was contained in D Wing and the rest of the institution remained quiet.

The spokesman said: "We are still not sure what caused it and no demands were made by the prisoners.''

Police confirmed yesterday that a criminal investigation was under way and that an internal prison service investigation had also started.

In February a "Tornado Team" of prison officers from Doncaster used 18 stun grenades to break up a seven-hour dispute in the prison chapel.

Zico Reid, 18; Nathan Walters, Desmond Noonan, Carlos Butler, Nathan Hogg and Ramone Brown, all 19 and from the Manchester area, have since appeared in court charged with prison mutiny. The case is continuing.

Last night, the charity the Prisoners Reform Trust voiced concerns about the care given to young offenders in general.

"We are concerned about this age group in general because they are a vulnerable and volatile group of young people," said director Juliet Lyon.

"Young offenders institutions do not really have the level of staff necessary to give these young men the kind of close supervision and support that they need.''

But Barnard Castle Town Mayor John Yarker, who was a prison officer at Deerbolt for 20 years, said he had every confidence in Deerbolt.

He said: "Staff are very well trained for these incidents and they can react in a very professional manor.

"Both of these incidents were contained and the perimeter is very, very secure so I do not think there is any concern for the safety of the people in the town.''