Specialist guards have been deployed in a Worcestershire prison after a group of inmates caused a disturbance in part of the building.
Ten prisoners caused staff to retreat from a wing of HMP Long Lartin on Tuesday evening while damaging part of the building.
Prison staff were attacked with pool balls and one officer went to hospital after indirectly sustaining an injury in the incident.
A specialist unit of prison officers, known as a Tornado Team, have been sent to the category A prison in an attempt to restore order.
A Ministry of Justice spokeswoman said: “Specialist staff have been deployed to manage an ongoing incident at HMP Long Lartin.
“We are absolutely clear that prisoners who behave in this way will be punished and face extra time behind bars.”
Prison Officers’ Association general secretary Steve Gillan tweeted: “At moment we do not know all the facts but we fully support all our members at Long Lartin who are clearly facing a difficult evening with a disturbance.”
HMP Long Lartin is one of five high-security “dispersal” establishments and holds some of the most dangerous offenders in the country.
The high-security prison has the capacity for 622 prisoners and is believed to currently hold around 500.
A year ago six prison officers were injured after prisoners tried to take over a wing at the high-security prison.
According to a 2018 report into the prison following another serious disturbance in October 2017 involving 81 prisoners, about 75% of the prisoners were serving life sentences.
A quarter of all inmates were classed as category A or high-security offenders.