Investigation into prison siege

The jail was changed from a Category B to a Category C prison

A inquiry by the Prison Service is under way after inmates took a fellow prisoner hostage at a Devon jail.

The incident took place at Dartmoor jail and resulted in a five-hour siege.

The situation was resolved peacefully by trained negotiators who were called to the Category C prison at about 2300 GMT on Tuesday.

The Home Office has not said why or how the incident took place, but that it was a "serious" but not uncommon low-level incident.

Four inmates took the other prisoner hostage.

There is no evidence the population at Dartmoor is any different from that of any other Category C prison in the country Home Office spokesman

Those involved have now been transferred to other prisons.

There were no injuries to staff or prisoners.

Dartmoor Prison was re-categorised from a Category B prison to Category C in 2001.

BBC South West Home Affairs correspondent Simon Hall said: "The Prison Officers' Association has concerns that the re-categorisation was accompanied by a reduction in the number of prison officers, which it believes has left its margins of safety too slight.

"There are also concerns that some prisoners that are higher risk than should have been sent to Dartmoor."

Two incidents

"This will be a setback for the prison, which had been getting better after some damning reports, but a relatively minor one."

A spokesman for the Home Office said there had only been two incidents of "substantial concerted indiscipline" at Dartmoor since it became a category C prison in April 2001.

In a statement, he said: "Prisoners are categorised according to the likelihood that they will seek to escape and the risk that they pose should they do so.

"Appropriate prisons are maintained for each category of prisoner. It is not the case that prisoners are reclassified in order to create space within certain areas of the estate.

Prisoners transferred

"However, prisoners are categorised at the lowest appropriate level in order to facilitate rehabilitation.

"Allocation of all prisoners to any part of the estate takes into account factors such as public protection, security and regime.

"There is no evidence the population at Dartmoor is any different from that of any other Category C prison in the country.

"On occasion, Dartmoor will receive difficult prisoners transferred from other establishments, as will all other Category C prisons.

"The area manager and the prison governor are monitoring this type of incident closely, and the South West area is currently working on a protocol for dealing with the more disruptive prisoners in the area."