The former MP for Tooting is planning to set up an independent London Drugs Commission which will investigate the potential health, economic and criminal justice benefits of decriminalising the Class B drug.
Although he has ruled out decriminalising Class A drugs such as heroin and cocaine, Mr Khan is said to be willing to consider supporting changes to the legal status of cannabis if that is what the commission concludes.
The Labour Mayor, who is fighting off competition for City Hall from 20 candidates including Tory Shaun Bailey and actor Laurence Fox, believes there is huge public support for a more relaxed approach to decriminalisation.
However, formally adopting such a position could put him out of kilter with Labour leader Sir Keir Starmer, who recently said he opposes decriminalisation.
Sadiq Khan will launch a review examining the possibility of decriminalising cannabis if he is re-elected as Mayor of London on May 6 (pictured at Savoy Place)
Protesters smoke cannabis during a demonstration calling for cannabis to be legalised at a 420 Day event in Hyde Park in London, on April 20, 2014
The policy proposal to set up the London drugs commission is expected to be published in Mr Khan’s mayoral election manifesto on Tuesday.
A source close to the mayor told the Guardian: ‘It will be for the commission to look at the evidence in the round, but nothing is off the table in the context of what is best for public health and keeping Londoners safe’.
Mr Khan is expected to announce this week that the decriminalisation of cannabis will counter the illegal drugs trade and organised and violent crime.
The mayor’s office said the illegal drug trade in Britain is estimated to cost society almost £20billion per year, with nearly 42,000 people in England and Wales charged with drugs-related offences last year.
Some estimates suggest that legalisation and the regulation of the sale of cannabis would raise at least £1billion in taxes for the cash-strapped Treasury.
The London drugs commission would be comprised of independent experts from criminal justice, public health, politics, community relations and academia.
It is expected to examine how countries around the world have tackled problems with drug use and addiction, including Portugal, Canada, Uruguay and several US states – where cannabis for recreational use is legal.
The commission would report to the mayor with recommendations for City Hall, the Government, the police, the criminal justice system and the NHS.
A young woman smokes cannabis during a demonstration calling for cannabis to be legalised at a 420 Day event in Hyde Park in London, on April 20, 2014
The Mayor of London believes there is widespread public support for a more relaxed approach to decriminalisation. His campaign team cited polls showing more than half of the UK, and nearly two-thirds of Londoners, support decriminalising cannabis for recreational use
Although Mr Khan does not have the powers to introduce new laws, the Guardian reported that the mayor believes an official endorsement would give calls to decriminalise cannabis a major boost.
Mr Khan told MailOnline: ‘It’s time for fresh ideas about how to reduce the harms drugs and drug-related crimes cause to individuals, families and communities.
‘The illegal drugs trade causes huge damage to our society – driving serious and violent crime, damaging people’s health and criminalising too many young people.
‘If re-elected, I will establish a new London Drugs Commission comprised of independent experts to examine the latest evidence from around the world.
‘The commission will make recommendations focusing on the most effective laws to tackle crime, protect Londoners’ health and reduce the huge damage that illegal drugs, including cannabis, cause to our communities and society.’
Sir Keir Starmer has called the current drugs laws ‘roughly right’, but added there was ‘always room for a grown-up debate about how we deal with these cases’.