The number of prisoners in Northern Ireland’s largest prison has risen by 48 per cent in five years, from 830 prisoners at the time of the last inspection to 1,050 at the unannounced inspection in October 2022 and 1,230 this week.

More than half of those currently held in Maghaberry are there on remand.

Jacqui Durkin, the chief inspector of criminal justice, said: “When inspectors visited Maghaberry in September and October 2022, we found a decline in performance against the ‘healthy prison’ tests since the last inspection in 2018 and identified a number of concerns which included access to drugs and significant areas for improvement in the delivery of education, skills and work activities.

“Inspectors identified there was a serious drug problem at Maghaberry at the time of the inspection with 41 per cent of prisoners surveyed during this inspection indicating it was easy to get illicit drugs at Maghaberry while 28 per cent told us they had developed a drug problem while they were there.

“We found there was no effective or co-ordinated plan in place to reduce the demand for and supply of drugs and no means of assessing the effectiveness of actions taken. This needs to be addressed as a priority.”

Prisoner access to education, training and work activities had also declined, which was restricting opportunities for men held at Maghaberry to develop practical skills.

Ronnie Armour, director general of the Northern Ireland Prison Service, said: “While the findings of inspectors are of course disappointing, they are not surprising. For some time we have been highlighting the impact of the pandemic on the prison system and our struggle to recover in the context of a rapidly rising prison population.”

He added: “While it is important that we don’t seek to make excuses for the decline in service delivery at the prison since the pandemic, no-one should underestimate the pressures prison staff are currently facing. It is important to recognise the exceptional work staff undertake with some of the most complex, challenging and dangerous members of our community.

“Like our hospitals, ambulance service, police and other front-line services, the current demands placed on prison officers is unprecedented. We are not complacent about the issues Inspectors have raised, indeed we are determined to address them, however it is important to recognise that due to the context in which we are operating in, this is likely to be the case for some time to come.”

Mr Armour said the introduction of X-ray body scanners at Maghaberry had already begun to have an impact on the availability of illegal drugs and action was being taken to prevent abuses of prescription drugs.

He also said allegations about the mistreatment of Catholic prisoners would be taken “very seriously” and he has urged the chief inspector to “encourage those who made the allegations to make a formal complaint that can be properly investigated”.