A group of cross-party MPs have backed a report which urges the government to follow several US states in legalising cannabis and describes the UK's current drug policy as "an embarrassment". The report by the Adam Smith Institute think tank said the legalisation and regulation of the Class B drug is the "only workable solution" to problems such as crime and addiction in the UK and claims doing so could add more than £1bn ($1.2bn) in tax revenue every year.

It also claims that legalising cannabis could see a huge reduction in the number in the number of prisoners behind bars, with the number of cannabis-related offenders in England and Wales currently at 1,363, costing the taxpayer £50m a year.

The report says the UK needs to follow in the steps of the US, with eight states already decriminalising the drug for personal or medical use so far, with four additional states – California, Massachusetts, Nevada, and Maine – becoming the latest ones to fully legalise cannabis.

According to the report, more than half of the British public and three quarters of MPs believe that Britain's current drug policies are "ineffective and a new approach is needed".

Former deputy prime minister Nick Clegg and co-leader of the Green party, Caroline Lucas, and former home secretary Jacqui Smith are among those to have shown their support for the report.

It says: "The World Health Organisation agrees that prohibition has led to policies and enforcement practices that entrench discrimination, propagate human rights violations, contribute to violence related criminal networks and deny people access to the interventions they need to improve their health. The British Medical Journal has come out in support of legalisation, stating that the ban on the production, supply, possession and use of some drugs for non-medical purposes was causing huge harm."

Showing his support, former Liberal Democrat leader Clegg said: "British politicians need to open their eyes to what is happening in the rest of the world. Cannabis prohibition is being swept away on a tide of popular opinion and replaced with responsible legal regulation. Now is the time for Ministers to start writing the rules for this legal market, including age limits and health warnings, so that we can finally take back control from the criminal gangs."

Nick Clegg
Former deputy PM Nick Clegg backs the legalisation of cannabis Getty

Lucas added: "The 'War on Drugs' has been an abject failure, and the continued criminalization of cannabis users is deeply counterproductive. Britain needs an evidence-based drugs policy, rather than continuing the expensive and ineffective prohibition regime."

Countries such as the Netherlands and Portugal have also decriminalised the drug, with also Germany also set to fully legalise cannabis. The report described Canada as a country which is "paving the way" for full legalisation and regulation.

Sam Bowman, Executive Director at the Adam Smith Institute, said: We have a growing body of evidence from abroad that legalisation and smart regulation are much better ways of curbing the harms cannabis can cause to users and their communities, and that straightforward bans just push users into the hands of criminals. Cannabis is enjoyed by many otherwise law-abiding people and making criminals of them makes an ass of the law – the only sensible approach now is to legalise and regulate."