The remarks will stir the controversy about behaviour and come only two weeks after Professor Pamela Munn of Edinburgh University, the school ethos champion, proclaimed that the moral panic about rising indiscipline was mostly mistaken.
Inspectors base their findings on regular classroom visits across the country and are currently reviewing how schools are implementing the recommendations of the national discipline task force set up by Jack McConnell, now First Minister. They will report later this year.
Bill Maxwell, chief inspector, writes: "Inspections continue to reveal a relatively small but nevertheless significant proportion of schools - approximately 5-10 per cent - that are experiencing substantial problems with poor behaviour and indiscipline, often, but not exclusively, in the secondary sector. The proportion is similar to the equivalent figures reported south of the border."
Mr Maxwell adds: "Where such problems occur, the impact can be very severe with widespread detrimental effects."