The Accounts Commission has stepped up the pressure on the new education authorities to close half-empty schools with the publication of a follow-up report to its Room for Learning study.
The study, published last year, urged councils to close more than 100 schools which had surplus capacity and where suitable alternatives existed nearby.
The commission, which audits the accounts of Scotland's councils and local health authorities, estimated that closures would save councils Pounds 25 million a year. A further one-off savings of Pounds 20 million would come from reduced maintenance costs.
Managing Surplus Capacity in School Buildings, the latest report, is intended to be a management guide and outlines "the key features of an effective consultation process" in carrying out closures. It was produced jointly with the Association of Directors of Education in Scotland.
Councils throughout Scotland are currently struggling to make the case for closures to their electorates. The commission urges them to concentrate on the one-third of primary schools and one-quarter of secondary schools that are less than 60 per cent occupied.
The report acknowledges that "schools rationalisation is a difficult process, not least because it is set firmly in the political context. For any proposal to have the potential for success, it must have the support of councillors. That support will depend on them being convinced of the improvements in educational provision which will follow any restructuring exercise."
Bob Black, controller of audit at the Accounts Commission, said the situation would continue to be monitored.