A vote of no confidence in the governor of a young offenders' institution hit by rioting has been delivered by the Prison Officers Association (POA).
The POA claims there is a problem with rival gangs in the institution
A wing at Deerbolt, near Barnard Castle, County Durham, was taken over by inmates for five hours on Tuesday.
On Sunday, four prison officers were injured at the premises during a riot.
The Home Office said votes of no confidence were not unusual and the POA's action would have no impact on how Deerbolt was run.
The POA had earlier claimed the institution was "under-resourced and undermanned", but this was denied by the Home Office.
Steve Cox, national vice-chairman of the association, said the vote, by 54 prison officers on Wednesday, had been unanimous.
He said: "From the outside it looks as if the riots have prompted this action but the staff at Deerbolt were actually calling for a vote before the disturbances.
"They have been warning that the situation has been getting worse in terms of assaults and threats on officers by inmates and they are angry that no action has been taken."
He added that Deerbolt was undermanned at a time when the institution was holding violent prisoners from other parts of the country due to overcrowding.
Officers wanted the governor to spend more of its budget on improving staffing levels and less on bureaucracy.
On Sunday, one prison officer was left with a fractured skull after an eight-hour riot involving 40 young offenders on one wing.
The POA said the officer had been repeatedly kicked and hit by young offenders.
Another wing was taken over by inmates on Tuesday and the rioting was only brought under control by the Prison Service in the early hours of Wednesday.
There have been no official reports of injuries.
A statement released on behalf of the Home Office after the disturbance on Tuesday said: "A full investigation will be taken by outside managers.
"Deerbolt was within its operational capacity, was not under-resourced and was not undermanned.
"A police investigation is also under way and it would be inappropriate to comment further while this is ongoing."