After a multi-million pound expansion of the sector over the last five years, too many beds are now lying empty, according to minutes from a meeting of Scottish Government officials, the heads of secure units and local authority representatives. The meeting concluded that "secure units are going to have to shrink, whatever happens", with some providers reporting they were "already looking at closing units imminently".
However, one potential solution is to move some of the 16 and 17-year-olds currently imprisoned in Polmont Young Offenders Institute to the unfilled places in secure unit facilities, said Graham Bell, one of the members of the Securing our Future working group.
The group will meet for the first time later this month to discuss the over-capacity problem, which experts say has been caused by community- based alternatives being developed at the same time as secure unit places were being expanded.
The use of secure unit places for 16 and 17-year-old prisoners was one of the recommendations made by the Scottish Prisons Commission, chaired by Henry McLeish, in July. Putting young people in prison damaged their educational chances and job prospects and forced them to "form relationships with and, no doubt, learn from more experienced offenders", it said.
At more than pound;4,000 per person per week, the cost of secure unit placements for youngsters who have committed serious crimes or who are a danger to themselves are not always good value for money, argued Michelle Miller, chair of the children and families committee of the Association of Directors of Social Work.
In 2002, the then Scottish Executive announced plans to expand the number of secure unit places from 90 to 125, at a cost of pound;45 million. At the time, the SNP accused the Labour-Liberal Democrat coalition of not going far enough, and during the 2003 General Election, it called for places to be doubled to 180.
Now, however, a freedom of information request has revealed that earlier this year, secure units were having to close sections because of under-use and some units were only three-quarters full.
In February, three secure units in the west of Scotland - St Mary's Kenmure, St Philip's and the Good Shepherd Centre - had a combined total of 84 beds, but 21 vacancies.
Rossie School in Angus was only three-quarters full at any one time, with a budget deficit of around pound;500,000.
Meanwhile, the secure unit at the Kibble Education and Care Centre in Paisley, which opened in 2007, was running at 78 per cent occupancy.
More recently, units have filled up due to the closure of St Mary's Kenmure, following rioting in April. But St Mary's is in the process of reopening, which will again reduce occupancy elsewhere.
The over-provision in the secure estate could serve Scotland well, claimed Graham Bell, who is also the chief executive of Kibble. Every system needed slack, he argued, and additional places in the secure sector might allow Scotland to end the much-maligned practice of sending 16 and 17- year-olds to prison.
He said: "This allows us to do something for that age-group which, in the past, we frankly could not do."
A Scottish Government spokesman said that it was aware of the spare capacity issue and was working "closely and imaginatively" with providers to ensure the continued use of places in secure units.