In its new family information booklet, the Irish Prison Service (IPS) warns that drug overdose “is now the main threat facing your loved ones in prison”.

It continues: “We need your help to keep them safe. During the past few weeks your loved one may have stopped using or reduced their drug use. As a result they will have lower tolerance levels.

“There is a huge risk of them overdosing if they start using again.”

The booklet advises prisoners’ families to refuse to bring drugs into prison and encourage prisoners to seek “support available in all prisons for people struggling with addiction”.

As of yesterday, physical family visits to Irish prisons have recommenced on a phased basis, subject to ongoing risk assessment and the latest public health advice.