There have been fresh calls for the Ministry of Justice to review staffing levels in light of the most recent incident at HMP Swaleside.

A prison officer was slashed across the face with a blade during a major disturbance at the Eastchurch site yesterday and has now been discharged from hospital.

Andrew Neilson, director of campaigns at The Howard League for Penal Reform, said the number of prison officers in the jail has been cut by a quarter in the last four years which meant the incident did not come as a "massive surprise".

He said: "It is a very unsafe prison. The prison I think had about 30 assaults on prisoners, 11 on staff in the six months prior to it being inspected.

"There were prisoners who had been stabbed or slashed and we were talking about the fear that there were weapons readily available in the prison and this has come to a head unfortunately with the incident yesterday.

"Staff should not be put in that situation and neither should prisoners.

"When there's a disturbance it may started by prisoners but it won't be all the prisoners in the prison.

"There will be many prisoners who are trapped in that just the same as the staff are so it is something that is very serious and the Ministry of Justice has to look at its policies."

Friday's incident began just after 5.30pm a series of "small fires" started at HMP Swaleside and Kent Fire and Rescue was called.

The prison officer was then injured, suffering wounds to his face believed to have been caused by a bladed weapon.

He was airlifted to hospital but has now been discharged.

The trouble involved just two prisoners who climbed onto netting strung between walkways designed to stop items being thrown to the ground.

A spokesman for the Ministry of Justice said this was an "isolated incident" and was resolved at about 10.30pm last night with both prisoners involved now being kept in segregation.

He said everything at the prison is now "back to normal" with general order restored.

Other prisoners were confined until the situation was brought under control.

The Home Office dispatched its specialist Tornado unit to the jail, a group of officers specially trained to quell prison riots.

Accommodation areas are believed to have born the brunt of the fire damage, and fire crews used breathing gear to enter the prison and extinguish the flames.

A large group of prison officers was seen leaving Swaleside just after 9.30pm, believed to be the Tornado unit.

Just a week ago Swaleside was slammed by HM Inspectorate of Prisons which blamed staff shortages for a variety of problems at the category B jail.

Serious issues raised by the report included a number of serious assaults on staff and inmates, with some prisoners too frightened to leave their cells.

Last month another report by an Independent Monitoring Board raised concern over the number of weapons found at the prison.

Peter McParlin, national chairman of the Prison Officers Association, said the prison service was under immense pressure due to staffing shortages.

He said: "We've told management, we've told them about the pressures faced by staff, but they haven't listened."

The National Offender Management Service said the prison has been supplementing officers with temporary staff in an attempt to fill vacancies.

Gordon Henderson, MP for Sittingbourne and Sheppey, said his heart went out to the injured officer.

He added: "I raised the issue of increased violence in our prisons a few weeks back in Parliament and urged the prisons minister to meet with my local POA representatives to hear what problems they face.

"I was given an assurance that a minister will visit Sheppey and I very much hope that will happen as soon as possible.

"My heart goes out to the injured officer and his colleagues who face similar threats on a daily basis. These guys need support and I am determined to give it to them."