An independent prison watchdog has raised concerns over a “scourge” of synthetic cannabis usage at Suffolk’s HMP Highpoint.

The findings come following an inspection of the prison by the Independent Monitoring Boards (IMB), who highlighted concerns over the use of drugs – including spice – throughout the centre.

Spice, a synthetic form of cannabis or “new psychoactive substances”, has been said to cause unpredictable behaviour among inmates on a regular basis – while the report also detailed risks to staff health by “ingesting the fumes”.

Of the 388 drugs found, 79.3% were spice – with cannabis and cocaine as well as “other” drugs, including unknown white powder or pills, also ranking high.

IMB’s annual report regarded the drugs problem as a “scourge”.

The report read: “The scourge of drugs entering the prison in all its forms has an impact on the day-to-day regime, and extra resources and staff are needed to tackle this difficult issue.”

One method of getting the substances into the prison included hiding them under postage stamps, while others were thrown over the prison walls.

The watchdog recognised however the work done by the staff and senior management team (SMT) in attempting to curb the problem, and said a national government strategy is needed to combat the scourge across the UK.

IMB Highpoint chair, Susan Feary, said: “We have raised these concerns with the governor, the Prison Service and ministers to address: However we recognise the hard work and dedication of the staff both uniformed and non-uniformed, and the SMT who have worked hard to make Highpoint a safe and positive place to live, their professionalism when dealing with everyday challenges is to be commended.”

The prison’s D Wing offers support to prisoners who wish to engage with drug recovery – which the watchdog said is a “safe and secure environment”.

A Prison Service spokesman said the government is investing £100m in prisons to halt the flow of drugs, weapons and mobile phones.

They added: “We are pleased that the board has again recognised the proactive efforts of staff to halt the flow of drugs through targeted searches.

“Security measures are being stepped up across the estate, including x-ray scanners, enhanced perimeter searches and more drug detection dogs.”