The number of drugs including spice found by prison staff in Norwich Prison has rocketed over the last five years.

In the 12 months to March 2018, 81 searches uncovered drugs within Norwich prison - five times more than five years ago.

Over the same period, 18pc of the mandatory drug tests conducted in HMP Norwich returned a positive result, figures from the Ministry of Justice and Her Majesty's Prison and Probation Service show.

In total, inmates failed 83 of the 450 tests conducted in the institution.

For the first time this year, the figures include psychoactive substances such as spice, the abuse of which has increasingly become a concern for prison staff.

The most common single drug type found to have been taken in Norwich was psychoactive substances, which was found in 52pc of samples.

Andrew Neilson, the campaigns director at the Howard League for Penal Reform, said: 'The rising number of drugs and mobile phone confiscations is a symptom of the problems in an overburdened and under-resourced prison system that is failing the public.

'Where there is drug abuse there is also debt and violence, and these problems have become more severe in prisons across England and Wales as overcrowding and staff shortages have taken their toll.

'The best way to reduce the supply of drugs into prisons is to reduce the demand for them. This means ensuring that prisons are properly resourced and prisoners are occupied with purposeful activity, such as work, education, training and exercise.

'Above all, we need to see bold but sensible action to reduce the prison population. This would save lives, protect staff and prevent more people being swept away into deeper currents of crime and despair.'

Reacting to the national numbers, Justice Secretary David Gauke said: 'New psychoactive substances (NPS) are a game changer for prison safety, and these statistics reinforce the scale of the challenge.

'We are addressing this head on, and our £7 million investment in prison security will further bolster defences via airport-security style scanners, improved searching techniques and phone-blocking technology.

'We are also adopting pioneering approaches such as our 'Drug Recovery Prison' pilot at HMP Holme House, which is leading the way in tackling the supply of drugs and putting offenders on a long-term path to recovery.'