Campaigners have urged the Government to rethink drug laws in light of a widely respected independent body likening cannabis use to "moderately risky" gambling or junk food.

The publication of a six-year study from the UK Drug Policy Commission (UKDPC) today reveals that the £3bn spent annually tackling drugs is not evidence-based and calls for a "wholesale review" of existing laws.

The body, part-funded by the Home Office, was launched in April 2007 to provide objective analysis of drug policy, independent of government interference and special interest groups.

Its report, "A Fresh Approach to Drugs", examined the effects of drug policy and makes recommendations ahead of the UKDPC being wound up this autumn. The report recommended recategorising the possession of small amounts of drugs for personal use as a civil and not criminal offence.

It said there was an argument for amending the laws relating to growing cannabis for personal use which might "go some way to undermining the commercialisation of production".

In England and Wales 160,000 people are given cannabis warnings each year. The National Treatment Agency for Substance Abuse says 2.8 million people in England use drugs, but only 300,000 use heroin and crack cocaine which "cause the most problems".

The UKDPC report said there are "some moderately selfish or risky behaviours that free societies accept will occur" and seek to limit but not prevent entirely, such as "gambling or eating junk food".