A report from WA's Inspector of Custodial Services, Eamon Ryan, has found that crisis care units in the state's prisons are not meeting the needs of inmates who are suffering acute mental health issues.

The findings come after two Indigenous deaths in custody in WA prisons in the past five weeks.

Last week a 31-year-old Aboriginal man died in Eastern Goldfields Regional Prison in Kalgoorlie, and in early March a 29-year-old Aboriginal man died in Casuarina prison in Perth.

In November, Kurin Minang human rights expert and law academic Dr Hannah McGlade urged the WA government to act immediately to address the overcrowding and poor conditions in the state's prisons.

Dr McGlade told National Indigenous Times at the time that the report released that month by OICS showed "the WA government approach to incarceration is failing and putting lives at risk. In the last month we've seen two Aboriginal men, younger men, die in custody".

"We urgently need alternatives to prisons, including bail hostels. The remand population is much too high. Bail conditions are reportedly onerous and placing increased pressure on prisons," she said.

The report published Thursday focussed on the WA's seven crisis care units and found them to be under "significant pressure" to meet demand.

"The key causes were found to stem from outdated infrastructure, increased prisoner population, and more people in custody who are at risk of self-harm or suicide. This has put additional pressure on mental health staff to discharge prisoners from crisis care units as soon as possible to free up beds," the OICS stated

Mr Ryan urged immediate action to address the identified issues.

"With the soaring adult prison population, which stands at just over 8,400, the extraordinary demands on mental health staff and crisis care infrastructure are only likely to increase rather than diminish," he said.

The report identified several prisoners who had spent a significant period in crisis care, which not only compounds capacity constraints, but also undermines prisoner wellbeing. It noted that some of these prisoners would be better managed in a forensic hospital setting, such as the Frankland Centre. However, the Frankland Centre has a limited capacity of only 30 beds and can only accommodate around 10 patients from prisons at any one time.

Data showed there is a significant shortfall in meeting the needs of even the most acutely unwell prisoners.

Mr Ryan said the report also found many prisoners reported feeling worse in crisis care.

"Prisoners said they experienced feelings of loneliness and isolation because of extended periods of time in cell and being managed on separate unlock regimes. Some reported not wanting to reveal their struggles to avoid placement in crisis care units, feeling it was akin to punishment," he said.

While mental health and therapeutic professional support was available to prisoners in crisis care, the report details how this was also limited due to critical shortages of mental health nurses, counsellors, and psychiatrists.

Physical design of crisis care facilities was found to not support psychological wellbeing. Units were noisy, lacked stimulation, colour and natural lighting which can ultimately affect mood and wellbeing. Dayrooms and recreation yards within crisis care units provided very basic amenities, with little access to meaningful activities or nature.

The report also documents a couple of exceptions to the situation, with Bandyup Women's Prison and Melaleuca Women's Prison having made efforts to soften the appearance of their crisis care units.

"Also notable, is the Bindi Bindi Unit in Bandyup Women's Prison as a specialist unit for women in crisis. There is also redevelopment work underway in Casuarina Prison which will include an upgrade to the infirmary and a new specialist mental health unit," it said.

The WA Department of Justice said it is "committed to providing prisoners with the best possible crisis care".

"Across Western Australian's custodial estate there are seven crisis care units (CCUs) where at-risk prisoners can be monitored and supported. A new CCU at Banksia Hill Detention Centre for young people is under construction and planning of CCU infrastructure upgrades for WA's biggest prison, Casuarina, is underway," a Department spokesperson said.

"Department staff actively monitor the demand for mental health services across the estate, directing resources to where they are required most to support those who are vulnerable and at risk. A recent funding boost will see more clinical and Psychological Health Services staff at Hakea, the State's biggest remand prison."

The Department said that since the review, additional CCTV has been installed in common areas, providing better coverage within the CCU at Hakea.

Department Director General Kylie Maj said the Department remains committed to providing the best possible care in a safe and therapeutic environment for prisoners at acute risk of self-harm or suicide.

"The growing prisoner population has seen more prisoners present with poor mental health," she said.

"This, in conjunction with limited bed capacity for prisoners at the State's only secure forensic hospital, has meant greater demands on mental health infrastructure and resources across the custodial estate to support prisoners needing crisis care."

Corrective Services Commissioner Brad Royce said short-term measures and long-term planning are aimed at the provision of appropriate infrastructure and adequate mental health resources.