U-turn on cannabis law by Clarke

Charles Clarke, the Home Secretary, has given the clearest signal yet that he plans to reclassify cannabis as a class B drug.

Charles Clarke, the Home Secretary, has given the clearest signal yet that he plans to reclassify cannabis as a class B drug.

Senior Home Office sources have told this paper that he has major concerns that the decision to downgrade cannabis has led to more people using the drug.

They say that he is determined to reverse the decision of his predecessor David Blunkett to relax the laws on cannabis, which mean police could once again prosecute people found with the drug.

Cannabis was downgraded from class B to class C in January 2004, but in March of this year Mr Clarke asked the Government's drugs advisers - the Advisory Council on the Misuse of Drugs (ACMD) - to investigate reports of a link between cannabis use and mental health problems.

This followed the publication of several studies which have suggested people who use the drug heavily may develop a paranoid reaction. The ACMD is expected to complete its review by the end of the year but it is understood that Mr Clarke is still minded to raise the classification of cannabis even if the advisers find there is no evidence of a health risk.

The Home Office source said: "The Home Secretary's decision will not just be based on the ACMD's response but also on any indications that there has been an increase in cannabis use."

A Panorama programme broadcast tonight will show that the brains of rats undergo specific physical changes when they are given cannabis regularly.

This new research will also reignite the controversy surrounding whether cannabis is a "gateway" drug to harder substances such as heroin. The study at the Karolinska Institute in Sweden claims that rats exposed to cannabis in adolescence were more likely to want heroin.

However, mental health charities said that changing the classification of cannabis for a second time would not stop people using the drug but instead put more of them in jail.

Turning Point, which provides support for people with drug and alcohol problems, said it supported the original change in classification because it would free up police to focus on harder drugs.

"A lot of the evidence suggests that usage has not risen among young people," said a spokesman.