A vulnerable woman was repeatedly sexually assaulted after being released from a Belfast prison 13 times, a report has said.
Appropriate arrangements were not put in place to ensure continuity of care between Ash House in Belfast and the community, the Council of Europe human rights organisation said.
The watchdog made a series of more positive findings, but called for the authorities to screen newly admitted women for sexual abuse.
It said judges had questions to answer in one case of repeated admission to custody.
It said: "Not only is prison in general a totally inappropriate environment for such a vulnerable woman, but Ash House is notably under-resourced to provide the care that this woman requires.
"This case raises issues of great concern around the quality of care and support for vulnerable persons in Northern Ireland, including as regards the role of criminal courts."
Ash House is a dedicated women's prison and the committee made positive findings surrounding the general actions of staff and conditions of detention.
The review from the council's Committee for the Prevention of Torture (CPT) warned about low staff numbers "threatening safety".
It highlighted concerns surrounding the treatment of a small number of women at Ash House, including one who did not see a psychiatrist after she was first admitted in 2014.
It added: "Her records show clearly that her condition continued to deteriorate over time and her clear vulnerability; she was discharged repeatedly into situations where she was apparently the victim of sexual assaults."
The report highlighted the case of another woman with a history of self-harm, drug misuse and depression admitted to Ash House at the end of 2016.
It said: "It was noted that her behaviour was bizarre and that she was disorientated and later she was found to be hysterical, shouting in her cell and seeing spiders."
It took four weeks for her to see a GP and she was not seen by a psychiatrist before her release early last year.
She was readmitted to prison twice.
The report said: "She was repeatedly displaying challenging behaviour, which had resulted in several instances of control and restraint by staff.
"Again, no plans were in place at the time for her transfer to a more appropriate care environment and the CPT particularly laments the lack of psychiatric input into the care of this woman."
It recognised extensive reform in the prison service more generally and said alleged physical ill-treatment levels at the high-security Maghaberry Prison in Co Antrim were "greatly diminished" and most inmates felt safe.
The South Eastern Health and Social Care Trust administers treatment in prison through its GP and community services, with the prison healthcare team sharing relevant information.
A protocol has been agreed for those requiring transfer to mental health services involving close liaison with the health trust.
The GP is the gateway to access mental health services, including non-specialist ones.
The trust said many prisoners were affected by domestic abuse, homelessness and poverty and may therefore require support from a range of organisations.
It said: "These social factors can impact on emotional well-being and resilience and cannot be addressed by health in isolation.
"Many people in prison struggle to engage with services offered in the community. The public health agenda seeks to address this and reduce health inequalities that exist in Northern Ireland."
That includes challenging people to change long-term lifestyle choices.
The Northern Ireland Prison Service said the report recognised extensive reform and transformational change.
It said: "The NI Prison Service is committed to striving for continuous improvement and is determined to build on the progress made to date."