Gordon Brown is set to brush aside the views of drug experts and press ahead with toughening up the laws on cannabis.

A report on the classification of the drug by the Advisory Council on the Misuse of Drugs (ACMD) was handed into the Home Office yesterday but the Prime Minister's decision, which will prove controversial in some circles, is not due until next week at the earliest. His spokesman made clear how the UK Government had "a statutory duty to take into account the advisory committee's advice so there will need to be proper consideration of what they have to say once we've seen the report in full".

The 23 experts, including doctors, police, judges and drug counsellors, are understood to have concluded that cannabis should remain in the Class C category - a "soft" drug after being downgraded from Class B in 2004, which made possession largely a non-arrestable offence.

However, Whitehall sources indicated Mr Brown was determined to push through reclassification to make cannabis a "hard" drug.

One said: "Mr Brown has made clear that, notwithstanding the scientific evidence, there are other considerations. These include expressing concern about the involvement of serious crime in the cannabis trade and sending a signal as a government and as a society that this drug is a danger to health."

Last month, the PM made his personal view clear when he said: "If we are sending out a signal, particularly to teenagers and particularly to those at the most vulnerable age, young teenagers, that in any way we find cannabis acceptable, given all we now know about the change in the way that cannabis is being sold in this country, that is not the right thing to do."

Last night, David Davis for the Conservatives said the reclassification could not come "a moment too soon". "While Gordon Brown has dithered over this, more than 24,000 people - including nearly 9000 under-18s - are estimated to have been forced to seek treatment for cannabis misuse in England alone," declared the Shadow Home Secretary.

"One cannot underestimate the real harm cannabis can do to a young person. The demotivating and debilitating effect cannabis can have at the most crucial stage in a young person's development can seriously harm their life chances."

However, going against the views of the ACMD will spark a major political row and could trigger resignations from the expert body, which plays a crucial role in setting Britain's drug policy.

The Liberal Democrats, who believe the UK Government should abide by the experts' view, demanded the ACMD's opinion should be published.

Chris Huhne, the party's home affairs spokesman, said: "The government must stop playing politics and publish this advice as soon as possible."