British officials are examining a pioneering Portuguese anti-drugs programme that decriminalises possession of substances including heroin and cocaine.

Controversial when it was first introduced almost a decade ago, the move has turned possession into an "administrative offence", which sends those caught with drugs for personal use to a so-called dissuasion board rather than having them prosecuted.

The board, which consists of social workers and psychologists who interrogate users on their drug habit, has the power to impose a variety of sanctions, including fines, or recommend treatment. Users caught with drugs more than once are ordered to appear at police stations or a doctor's surgery.

According to a senior official at the institute for drugs and drug dependency at Portugal's ministry of health, it was approached by the UK government about a month ago for advice on how it had managed its drugs programme since 2001.

Home Office sources said yesterday they were looking at various models and programmes during a consultation period over a new drugs strategy and that the government was talking to a number of experts to ascertain what worked. The consultation had been expected to lead to a more abstinence-based approach to tackling drug use.

It follows the recent resurgence in the debate over Britain's drug policies which saw Professor Sir Ian Gilmore, who recently stepped down as head of the Royal College of Physicians, call for the government to reconsider "decriminalising" all drug possession. His comments followed similar remarks by Nicholas Green QC, chairman of the Bar Council of England and Wales, who said it was "rational" to consider "decriminalising personal drug use".

He added that he had also been persuaded by an article in the British Medical Journal, which argued that the prohibition of drugs had been "counterproductive", making many public health problems worse.

Officially, however, ministers remain resistant to the idea of decriminalisation. A Home Office statement yesterday said: "The government does not believe that decriminalisation is the right approach. Our priorities are clear; we want to reduce drug use, crack down on drug-related crime and disorder, and help addicts come off drugs for good."

David Cameron and Nick Clegg stated their support for drug law reform before entering frontbench politics. As a member of the home affairs select committee inquiry into drug misuse in 2002, Cameron voted in favour of a recommendation that the then government moved to discuss alternative policies "including the possibility of legalisation and regulation".

In the same year, Clegg also supported the legalisation of drugs – including measures for heroin to be made available under medical supervision – while he was a member of the European parliament.

The approach to Portugal, which has seen a fall in levels of petty crime associated with addicts stealing to buy drugs, as well as a drop by a third in the number of HIV diagnoses among intravenous drug users, is significant. Despite decriminalisation, it levies more fines than the UK and drug use has not increased. Those opposed to similar moves in the UK have used the same arguments as the opponents of decriminalisation in Portugal.

The drugs minister, James Brokenshire, has indicated that the ultimate aim is to help the 210,000 problem drug users in treatment to achieve a drug-free life. Most are "maintained" on synthetic opiates, rather than pushed towards abstaining.

Experiments in tolerance

Portugal

In 2001, Portugal became the first country in Europe to officially abolish criminal penalties for possession of drugs intended for personal use. Spiralling addiction rates and rising costs in combating the sale and use of drugs forced politicians to act. Those found guilty of possessing small amounts are sent to a panel made up of a psychologist, a social worker and a legal adviser who will suggest appropriate treatment. Officials claim that the policy is working and that addiction rates have fallen.

The Netherlands

The Dutch classify cannabis in all its forms as a soft drug and the smoking of it, even in public, is not prosecuted. A system of licensed "coffee shops" is tolerated, and cannabis, although technically illegal, can be bought and sold in small amounts for personal consumption. Some Dutch politicians have moved to tighten these controls in response to worries about the approach encouraging drug tourism. The trafficking and sale of drugs remains illegal.

Switzerland

Zurich's Platzspitz Park allowed a needle exchange project for heroin addicts in the mid-1980s. Addicts openly brought heroin and injected themselves knowing that local police were ordered not to patrol the park. The experiment ended after the number of addicts in the park rose from a few hundred in 1987 to more than 20,000 in 1992.

Colombia

In February 2009, former presidents of Colombia, Brazil and Mexico said that the war on drugs was a "complete failure". César Gaviria, Henrique Cardoso and Ernesto Zedillo, all conservative politicians, called for a new strategy based on public health, including the legalisation of marijuana.

UK

In October 2009 the UK's chief drugs adviser, Professor David Nutt, was sacked for contradicting government advice on the harm caused by certain drugs. Nutt claimed that taking ecstasy is statistically no more dangerous than horse riding.

US

1996 Californian voters passed Proposition 215, allowing for the sale and medical use of marijuana for patients with Aids, cancer and other serious and painful diseases. The marijuana has to be recommended for approval by a California-licensed physician. The sale of medical marijuana is subject to local taxes.

May 2010 President Obama embarks on an agenda for tackling drug use with greater emphasis on prevention and "harm reduction". This signalled a step change from the "war on drugs" approach favoured by President Nixon 40 years earlier.

August 2010 Mexican president Felipe Calderón urged world leaders to at least debate the issue of legalising drug use. The beleaguered president spoke out after new figures showed that 28,000 people had been killed in Mexico's current drugs wars.

2004 In series three of the TV drama The Wire, right, a drugs-tolerance zone in a rundown area of Baltimore, known as Hamsterdam, is endorsed by the local police. The fictional experiment had mixed results, but the programme stirred debate with viewers.

Jason Rodrigues