A European anti-torture watchdog has condemned the treatment of prisoners with mental health problems in Scotland’s jails, after observing disturbing scenes in a women’s prison.

A report says one prisoner in Cornton Vale had bitten her arm through skin and muscle to the bone, another set fire to her hair and a third was sitting in isolation in a cell smeared with blood and faeces.

"The CPT found women who were clearly in need of urgent care and treatment in psychiatric facility” the Council of Europe’s Committee for the Prevention of Torture (CPT) says. “They should not have been in a prison environment let alone segregated for extended periods in solitary confinement.”

The report raises concerns about conditions in the men’s estate, too, particularly in relation to the amount of time prisoners spend in their cells, increasing violence against staff and other prisoners and a growing overcrowding problem.

The Mental Welfare Commission for Scotland described the report last night as “truly shocking”.

The CPT's findings are based on visits made during October of last year.

It's members say a number of concerning issues were observed including a gradual rise in levels of violence between prisoners and inmate-on-staff violence, which it said the Scottish Prison Service linked to problems with synthetic drugs the committee described as 'flowing into' Scottish prisons.

So-called Novel Psychoactive Substances are "almost undetectable" the report says.

Excessive use of detention and limitations on the daily regime for prisoners are linked to overcrowding and staff shortages, the report says.

As a result, some prisoners are segregated for extremely long periods - months and occasionally years, with some becoming insitutionalised in 'separation and reintegration' units in jails.

But it was the CPT's findings in relation to mental health among women prisoners which were the most alarming. "Prison staff were not trained to manage the highly disturbed women... At least five women with whom the CPT's delegation spoke had severe mental health issues requiring hospital treatment, care and support," the report says.

It notes that while male prisoners in a similar situation can be transferred to high security psychiatric care, the same option is not there for women prisoners.

Colin McKay, chief executive of the Mental Welfare Commission, said the findings were 'truly shocking' but reflected some of the Commission's own concerns. “We have been raising concerns since at least 2014 about the lack of high secure mental health care for women in Scotland. We know there are pressures on Scotland’s overcrowded prison system and forensic mental health wards and we know that work is in progress to improve them.

“We will urgently review what happened to these women before and after the CPT visit, to see what lessons can be learned," he added.

“As the Government acknowledge, there can be significant delays in transferring women who need psychiatric care to hospital. This is unacceptable. Equally unacceptable is the lack of provision for women with a diagnosis of personality disorder, who are deemed unsuitable for hospital admission. We agree with the CPT that a better alternative to a prison segregation unit must be found."

The Commission welcomed a forensic mental health review currently underway in Scotland, led by Derek Barron, but said ministers should act without waiting for it to be concluded.

"The Commission will be seeking urgent discussions with the Scottish Prison Service to ensure it is notified of any cases similar to those cited in the report in future." Mr McKay added.

Scottish Labour’s Justice spokesperson, James Kelly MSP, said: “This is a dark day in the history of the Scottish prison system."

He said thee CPT's comments were an indictment of the Government's mismangement of theprison system. "

“For the EU’s committee for the prevention of torture to publish such a damning report is an indictment of the SNP’s mismanagement.

“Our prisons are in crisis. The Justice Secretary should apologise to prison staff, inmates and their families for the series of errors which have led to this international embarrassment, and urgently come forward with a plan to start to end these shocking practices.”

An SPS spokesman said the service recognises overcrowding and NPS are a problem in prisons and actions are being taken to address this, including plans to replace Barlinnie and Cornton Vale and using technology to detect and prevent drug use.

He said SPS aims for prisoners to spend the shortest time possible in segregation.