The unwanted benchmark has been reached despite high-profile efforts to drive down prison numbers.
The Scottish Government is poised to introduce a presumption against prison sentences of 12 months or less – up from the existing three-month limit – as part of a drive to cut the number of inmates. Scotland has one of the highest incarceration rates across Europe.
The Liberal Democrats have been leading calls at Holyrood for a rethink, warning the existing system is unsafe for staff and inmates.
Scotland’s prison population hit 8,020 towards the end of last month, official figures show. This compares with a post-devolution high of 8,400 in 2012.
Lib Dem justice spokesman Liam McArthur said: “Scotland’s prisons are bursting at the seams. Taking incarceration rates back up towards the highest levels seen by the Scottish Parliament is not a sign of a progressive justice system.
“Two-thirds of Scotland’s prisons are officially overcrowded. This bumper prison population just isn’t sustainable. It’s putting prison staff and inmates at risk.
“The evidence shows that community sentences are better than prison at reducing the chance of people re-offending, meaning communities are safer.
“The savings that can be made from the new presumption against sentences of less than 12 months must be reinvested into making community-based sentences robust.
“We also need to prevent re-offending by giving people the skills they need to get on in life alongside intensive support with housing, welfare and healthcare before and after they leave prison.”
The Lib Dems conference last weekend passed motions calling for greater investment in community-based sentences, as well as boosting purposeful activity for inmates.
The party has also called for an expansion of mentoring, with new staff capable of working with people before and after they leave prison.
The Scottish Prison Service said there had been a fall in the number of young people in custody by more than a third. But the changing make-up of the population inside is contributing to the overall rise in numbers.
“We’ve got a lot more people in prison for longer,” a Scottish Prison Service spokesman said.
There were about 500 inmates serving life sentences in 2000, compared with more than 1,000 today.
“The period of time people spend in custody on a life sentence has risen from about 11 years to nearer 19-20 years,” the spokesman said.
“The number of people serving sex offences has gone up from about 500 in 2000 to over 1,400 now and the sentences attached to those individuals are longer.”