THE use of "legal highs" at a Teesside prison has led to an increase in violent incidents and serious mental health problems among prisoners, a report has warned.

An independent inspection of Holme House prison, in Stockton, revealed a "worrying increase" in the use of psychoactive substances - the most popular of which is Spice, a synthetic cannabis which can cause hallucinations and other side effects.

Violent incidents had gone up by 60 per cent between 2014 and 2015 - showing a "more violent and disruptive element within the prison population".

Inspectors from the Independent Monitoring Board (IMB) for Holme House added: "Ingestion of these substances has led to some particularly violent incidents putting at risk the safety of staff and other prisoners.

"Hearsay evidence suggests some prisoners are being forced to take these substances as a form of bullying."

The report also said the drug had taken a "terrible toll on some individuals with effects from which they will never recover".

Prisons Minister Andrew Selous, who visited the North-East today (Thursday) said: “I don’t call them legal highs, I call them lethal highs. There’s been 19 deaths linked to these drugs. They are an absolute menace.

"We have introduced a full body scanner in one prison and if it is successful we may introduce them to prisons elsewhere. We are going to get the education message out there about these drugs too.

“I would say to any family member visiting prisons, ‘don’t bring anything in, you are not doing anyone any favours'. These drugs can be lethal."

Terry Fullerton, North-East representative of the Prison Officers Association, said Spice had become the drug of choice for prisoners because it was so cheap. He said the problem was on the increase in every prison, not just Holme House.

He said: "The compounds are constantly changing and no-one really knows the long-term side effects. Short term it can cause psychosis, hallucinations and memory loss, and violence.

"Some of the prisoners have been shown back on CCTV of their behaviour while on this substance and they have no memory of what they have done."

He said prison officers inhaling second-hand vapour from the prisoners' drugs had sometimes had to take time off sick because they were experiencing volatile behaviour, such as anger or depression.

The IMB report also said "volatile and disruptive behaviour" had been more evident this year in the prison, which was overcrowded, although not to the same levels as previous years.

Staffing levels were also an issue, although sickness levels had come down in the last year.