The availability of illegal drugs into the Young Offender Institution in Rochester is providing a lucrative trade for dealers on the outside and may have led to the death of one inmate and resulted in serious mental health issues for others.

These are the findinigs of the Independent Monitoring Board in its annual report, which claims police should be doing more to prosecute suppliers.

But the watchdog says the prison is generally well run, providing a safe environment amid drastic cutbacks both in staffing levels and resources.

While the drug recovery unit, introduced two years ago, supports addicts, users who wanted to kick the habit they were being mixed with those with no intention of giving up.

The report, covering a period from April 2014 to March 2015, stated: “It is clear that the ‘sale’ of drugs to prisoners continues to be ‘big business’ earning huge profits for the drug traffickers, causing problems of health, debt, physical violence and self-harming.”

It continued that officers had found “significant finds” of drugs with most deals being struck on mobile phoned smuggled inside.

Godfrey Featherstone, board chairman said: “Despite the short-sighted decision of central government to drastically reduce prison staff numbers, this has been a year characterised by small successes at [Rochester] HMP/YOI.

"The amount of contraband entering the prison has been interrupted and new work of training opportunities have been created.

"However, there is a real risk that the lack of inward investment will not allow these improvements to be capitalised upon and this will represent a false economy when compared top the benefits of reducing the number of prisoners returning to the prison system.”

The prison in Fort Road houses about 150 inmates aged between 18 to 21 and adult category C prisoners.