Speaking to The TES Scotland on the eve of a national conference on the subject today (Friday), David Liddell, director of the Scottish Drugs Forum, said: “When you involve the police, you raise the stakes immediately and that makes dialogue with the pupils involved more difficult.”

In an interview that took place before this week’s headlines on drug misuse in schools, Mr Liddell suggested “informal agreements” between schools and police stations. Outside agencies should only be used as part of a structured approach and not as a knee-jerk reaction.

He also cautioned against excluding pupils. “Exclusion isolates pupils and closes down communication.” Schools needed to build trust and confidence so pupils can turn to them for help.

Alistair Ramsay, Glasgow’s adviser in health education and an adviser to the Home Office and Scottish Office on drugs, said the issues were “hugely complex” and posed real dilemmas for schools. Heads did not want to be portrayed as “soft on drugs” although they also wanted to support young people at risk. “But we cannot take the line of no exclusion under any circumstances,” Mr Ramsay said.

The council’s advice to schools was that the police should be involved immediately they were faced with a drugs incident, but as part of a multi-agency approach. This was followed successfully at Craigton primary where a boy aged 11 was found with heroin. The boy is not at the school at present although the authority has not excluded him.

Gordon Jeyes, director of education in Stirling, said the council’s guidance treated drug misuse as a child protection matter. “We should have zero tolerance to any sale of drugs in schools. But beyond that, we should take each situation as it comes.”