By politics.co.uk staff
The government's chief drug advisor has gone to war against the Home Office, in the latest episode of a simmering row between experts and the government.
Professor David Nutt, of the Advisory Council on the Misuse of Drugs, said cannabis did not cause major health problems and should have remained a class C drug.
He also repeated previous comments about ecstasy - that it is less dangerous than riding a horse - and said those who wished for the drug to be downgraded to class B had already won the argument.
In a wide ranging attack, he also said former home secretary Jacqui Smith "devalued" the concept of scientific research. The comment is a reference to the government's decision to return cannabis to class B status despite all the medical and official advice pointing against it.
The Home Office has distanced itself from his views.
Prof Nutt took aim at the way the debate around the reclassification of cannabis had centred on its ability to prompt schizophrenic episodes in some users.
But he claimed the risk was low, and that despite wide usage of the higher strength cannabis for over a decade there had been no discernable upswing in schizophrenic episodes.
He also quoted research which "estimates that, to prevent one episode of schizophrenia, we would need to stop about 5,000 men aged 20 to 25 years from ever using the drug".
Prof Nutt said: "We have to accept young people like to experiment - with drugs and other potentially harmful activities - and what we should be doing in all of this is to protect them from harm at this stage of their lives.
"We therefore have to provide more accurate and credible information. If you think that scaring kids will stop them using, you are probably wrong."
Prof Nutt made the comments during a lecture at King College.
Liberal Democrat home affairs spokesman Chris Huhne welcomed his comments.
"Professor Nutt is right to suggest that there needs to be a full and frank debate about drug abuse without resorting to moral hysteria," he said.
"The best way to reduce the harm drugs cause to society is to base policy on facts, not as a method of political posturing."