Prison inspectors have raised serious concerns about mental health treatment at Scotland's £140m "super-jail".

HMP Grampian opened in March 2014 as Scotland's first community prison, capable of holding more than 500 offenders of all ages.

On Wednesday, Her Majesty's Inspectorate of Prisons for Scotland (HMIPS) published its first report into the Peterhead jail.

Of the ten categories used to assess prisons, inspectors graded one "good", five "satisfactory", three "generally acceptable" and one "poor". They singled out issues with mental health treatment as an area of concern.

Prisons chief inspector David Strang said: "The overall assessment of healthcare provision in the prison was poor.

"In particular, prisoners with mental health needs faced a long waiting list and there was a need for formal assessment and improved care plans for all patients.

"The general relationship between Scottish Prison Service (SPS) staff and NHS staff was observed to be challenging, with scope for improved levels of joint working and mutual support."

Nurses reported being frequently "threatened and verbally abused" by prisoners, said they "did not feel safe" and told inspectors they were "unsupported by SPS staff" at the jail.

A total of 41 inmates were waiting to visit the prison's mental health team when inspectors visited.

Women had access to a weekly mental health clinic while men did not, they noted.

Inspectors said: "There was little in the way of preventative practices for supporting prisoners who were exhibiting self-harming behaviours.

"We observed limited treatment options for prisoners who were at risk of self-harm, and management and intervention was sporadic and inconsistent."

Staff in the women's wing of the prison told inspectors they were not being supported by management when dealing with prisoners at risk of harm.

Inmates said they felt like they were being punished for asking for protection and could spend up to 23 hours a day in their cell.

Meanwhile, inspectors also expressed disappointment that no young men were being held at HMP Grampian, despite the prison being designed to house offenders of all ages.

STV News revealed on Tuesday that no male prisoners under the age of 18 have been kept at the jail since July 2014 following a riot earlier that year.

HMP Grampian was designed as a "community-facing" prison which would house men, women and young offenders under the same roof. Inspectors said it was "disappointing" that areas of the "highest-quality prison estate in Scotland" were lying empty.

No young men have been moved back to the prison in the months since their inspection.

Despite their concerns, inspectors said they "found a prison which was fully-functioning and operating in a stable environment" and said the newly-opened family centre was an "excellent facility".

They said: "Overall, prisoners told us that they felt safe. Staff were respectful and courteous in their dealings with prisoners and there was evidence of positive engagement between staff and prisoners.

"The strongest area of performance in Grampian related to the preparation of prisoners for their successful return to the community."