Mental health charities have welcomed recommendations by the Advisory Council on the Misuse of Drugs for an education campaign and further research on cannabis, but do not want to see more stringent penalties for its use.

Rethink said the government's decision to move cannabis from a class C drug to class B was a mistake.

Rethink public affairs director Paul Corry said: "This decision goes against all the evidence. Use of the drug has gone down since it was downgraded to class C in 2004 and our research shows that only 3 per cent of users would consider stopping on the grounds of its legal classification."

SANE chief executive Marjorie Wallace said: "We would welcome a review of the whole drug classification system, and we do not wish to increase penalties, but while we live within the present system we need to give out an uncompromising signal about the specific links between cannabis and mental illness."

For more details, visit www.sane.org.uk and www.rethink.org