The number of prisoners in Northern Ireland waiting to receive treatment for opiate addiction has more than doubled in the space of a year.
Opiate substitute treatment is used to help addicts wean themselves off opiate-based drugs, such as heroin or fentanyl.
Health Minister Robin Swann said that 38 inmates in prisons here were actively waiting to receive such treatment as of December 2019.
This increased to 80 in November last year.
He was responding to an Assembly question from Alliance health spokesperson Paula Bradshaw.
Ms Bradshaw said: "Healthcare is provided to the NI Prison Service by the South Eastern Health and Social Care Trust, and I would call on them to work together to address this rising number of people awaiting Opiate Substitute Therapy (OST).
"I appreciate the fantastic partnership already in place between them and the first-class service they provide at present, so I would hope with additional resources and intervention, this number could eventually come down again.
"Our prisons are places for rehabilitation and OSTs are a key part of this."
A spokesperson for the South Eastern Trust said the waiting list for opiate substitute treatment in prisons here has grown in terms of numbers waiting over the past year and this is reflective of more people coming forward for treatment.
He added: "However, it is important to note that the waiting time for service users has not increased and the number of service users in the prisons on OST has almost doubled since January 2020 despite Covid restrictions."
In his answer, Mr Swann also detailed the number of people waiting to undergo opiate substitution treatment in each of Northern Ireland's health trust areas.
Belfast had the largest waiting list, with 41 people awaiting treatment in December 2019, increasing to 55 in November last year.
In the northern trust area the figure was two last year - the same as the southern trust.
Only one person was awaiting treatment in the south-eastern trust at the end of 2020, while seven were on the waiting list in the western trust - down from 10 in December 2019.
Earlier this month it emerged that there have been more than 50 deaths in Northern Ireland between 2014 and 2018 linked to the powerful opiate fentanyl, with a further five deaths between January and March 2019.
Fentanyl, which is prescribed to treat severe chronic pain, is 50 times more powerful than heroin and abuse of the drug has been more prevalent in recent years.
SDLP councillor Paul McCusker said users can buy fentanyl patches for as little as £10.
"I have personally dealt with a number of people who have used fentanyl and speaking to health professionals they advise that we haven't seen the full effects of this potent drug and fear that deaths will continue to increase," he said.
"Heroin and fentanyl are becoming easier to obtain and the supply of these types of drugs is on the increase, the worry is that when the individual buys the drugs they are unaware of what is contained in them, putting them at more risk."
In January 2020, the Advisory Council on the Misuse of Drugs (ACMD) warned that a rise in the number of fentanyl deaths in the UK was being driven by the drug being added to heroin.