A leading Scottish drugs official believes that Scotland can never win the fight against illegal substances.
Tom Wood said Scotland could never be a drug-free nation
Tom Wood, chairman of the Scottish Association of Alcohol and Drug Action Teams, said education and deterrence should take priority over enforcement.
"The message has to be more sophisticated than 'just say no' because that simple message doesn't work," he said.
However, the Scottish Executive said supply chains had to be tackled.
Scotland has one of the worst drug problems in Europe, with an estimated 50,000 addicts.
Mr Wood is a former police deputy chief constable and his organisation advises the executive on future policy.
"I spent much of my police career fighting the drugs war and there was no-one keener than me to fight it," he told the Scotland on Sunday newspaper.
"But latterly I have become more and more convinced that it was never a war we could win.
"We can never as a nation be drug-free. No nation can, so we must accept that.
"For young people who have already said 'yes', who live in families and communities where everybody says 'yes', we have to recognise that the battle is long lost."
He said it had to be accepted that decades of enforcement policies being prioritised had not been successful and instead the focus should switch to winning the arguments to persuade youngsters that "drugs are best avoided".
But an spokesman said: "We have a very clear policy on drugs, which is to balance the need to tackle supply and challenge demand.
Mr Stevenson called for a drugs summit to be held
"They have to go hand-in-hand and we make no apology for that."
Statistics released by the executive last week showed that there were 548 children and young people under the age of 16 and under coming forward for treatment in 2004-05.
Stewart Stevenson, drugs spokesman for the SNP, told the BBC's Politics Show, it was time for a high level debate about the way forward.
"It's time for a drugs summit that brings together the professionals with competing views, allows us to lay on the table quite challenging policy suggestions and look at the second and third level effects of implementing them," he said.
"If Jack McConnell won't do that I think he can be absolutely certain an SNP government, led by Alex Salmond next year, is very likely to make that an earlier priority."
Former Conservative leader David McLetchie told the programme: "I think any kind of discussion would be well informed by having some kind of independent chairman and independent research support.
"There can be far too many conflicting claims and competing factions.
"We need to have somebody that sits above that and brings elements together but is capable of producing some kind of objective judgement to help us map a way forward."