A prison officer suffered serious burns after boiling water was thrown in his face at a young offenders institution, which was recently criticised by inspectors for levels of violence.

An ambulance was called to Cookham Wood Young Offenders Institution and the officer was taken to hospital. His condition is not known.

The Prison Service has confirmed the incident happened, but refused to give any more details. Police are investigating.

A spokesman said: “A prison officer was taken to hospital following an incident at Cookham Wood prison on Tuesday, October 6.

“Any violence in prison is unacceptable, especially when it is directed at our hardworking staff. All incidents are fully investigated and prisoners found guilty can find their sentences extended significantly.

“Any violence in prison is unacceptable, especially when it is directed at our hardworking staff" - Prison service spokesman

“This incident has been referred to the police and it would be inappropriate to comment further while that investigation is ongoing.”

The South East Coast Ambulance Service (SECAM) was called to the institution on several occasions last week to take offenders to hospital after they had taken the legal high Spice.

The Prison Service said it took a zero-tolerance approach to such substances and worked closely with the police and the CPS to ensure those smuggling them in were caught and prosecuted.

A recent report, published by the chief inspector of prisons, revealed that one in 10 detainees at Cookham Wood are convicted killers.

Inspectors found in the six months up to March this year that there had been 61 assaults and 92 fights, some of which were very serious, at the institution in Sir Evelyn Road, which hold boys aged 15 to 18.

A recent search recovered 15 improvised weapons in just one wing of the prison. During his inspection, Nick Hardwick also found the levels of violence had soared with 21 staff assaults, some resulting in serious injury, from October 2014 to March 2015.

Force had been used against boys 400 times in those six months, compared with 282 during the six months prior.

Over a third of the teenagers stayed locked in their cells during the day, too frightened to mix with others.

At the time, Mr Hardwick said: “Behaviour management processes were weak and poor behaviour was not promptly challenged. Cookham Wood reflects the systemic problems we have identified across the YOI estate.”