A call has been made to fix the “broken” prison system after it emerged there were no offenders serving short term sentences at the open facility near Dundee.

Figures show that the number of inmates has fallen dramatically at Castle Huntly, with the bulk of the prisoners having received a custodial sentence of four years or more.

Labour MSP James Kelly said: “Castle Huntly is one of the best centres for rehabilitation in the prison estate, it should not have cells lying empty whilst other prisons have two prisoners living in cells designed for just one.

“If the Justice Secretary is serious about making our prisons safer and centres of rehabilitation then he must listen to Scottish Labour and urgently review the application process for transferal to HMP Castle Huntly.”

Scotland’s prison estate is soaring, with figures showing a near 9% year-on-year increase in 2018/19 to 8,212.

However, the number of prisoners at Castle Huntly - the country’s only open prison - has fallen by 29% over the last nine years.

In 2019, 188 inmates were based there, which stands in contrast to the 265 eight years earlier. In 2016, all 204 Castle Huntly prisoners were serving sentences of twelve months or more.

Kelly, who was recently appointed as his party’s Justice spokesman, is calling for the Scottish Prison Service to review whether suitable candidates on short term sentences are missing out.

He said: “Despite prisons across the country filling up to near or beyond capacity, the country’s only open prison, HMP Castle Huntly, is seeing a decline in the number of inmates it houses.

“Not a single prisoner in the facility has a sentence shorter than 12 months, with the vast majority serving lengthy sentences greater than four years."

However, a prison source said the long-term fall, as well as the absence of offenders serving short-term sentences at Castle Huntly, reflected pressure by MSPs nearly twelve years earlier.

In 2007, prisoner Robert Foye raped a teenage girl after being allowed to leave Castle Huntly to attend an Alcoholics Anonymous meeting.

The scandal led to a much more rigorous risk assessment process being put in place for eligible candidates who could be transferred to the open prison.

The insider said the enhanced vetting process was not suitable for short term offenders, most of whom would be released by the time the assessment was completed.

A spokesman for the Scottish Prison Service said: “The current numbers in open conditions reflect the rigorous risk assessment process which individuals have to go through in order to be progressed to open conditions.”