Karen Gillon told the conference: "If it's not happening, something will be done." Inspections of authorities would ensure that pressure was exerted.
Ms Gillon, who consulted both Jack McConnell, Education Minister, and Nicol Stephen, his deputy, before making her assertion, said: "The spirit of the McCrone agreement was to enhance the professionalism of teachers. It's not about clock watching. It's an attitude towards the school that is a professional one and ensuring that what happens outwith the 35 hours is as valuable as what happens within the 35 hours."
But she warned bluntly: "If we get intoa situation where people are only working 35 hours, we will have failed Scottish education. Teachers will have failed and we will have failed as politicians."
Ms Gillon, author of the Parliament's inquiry into school sport, believed that there was still a gap in the co-ordination and delivery of school sport that could be tackled by a specialist agency - the long-held view of the Scottish Schoolsport Federation. She encouraged the sports lobby to site its arguments within the social inclusion agenda and wider aspects of the curriculum.
The conference heard that pound;87 million of lottery money available for school sport through the New Opportunities Fund offered unprecedented opportunities - if the post-McCrone agreement on working hours did not scupper them.