He believes that a new approach is needed to tackle drug-related crime.
The Mayor tweeted: “It’s time for fresh ideas to reduce the harms drugs and drug-related crimes cause to individuals, families and communities.
“If re-elected, I’ll establish a London Drugs Commission – independent experts to examine the latest evidence from around the world.”
Sadiq Khan ruled out decriminalising Class A drugs like Crack and Heroin.
“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,” a source close to the mayor told the Guardian.
The announcement of the proposal to set up a London drugs commission is expected to be part of Khan’s mayoral election manifesto, published on Tuesday.
Mr Khan, who has in the past called for “an evidence-based conversation” around cannabis, will say: “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.”
Mr Khan, who in 2018 said he was opposed to relaxing the rules on recreational use, said: “The time is right for our society to have an evidence-based conversation about cannabis — about the law, how it is enforced, and how we support those struggling with addiction.
“It goes without saying that I will continue to support the police to enforce the law as it stands, but all Londoners will benefit if we can start a conversation that leads to a reduction in violent crime.”
Mr Khan in 2018 admitted smoking cannabis during a trip to Amsterdam “a long, long time ago”.
The Mayor of London was speaking to James O’Brien on LBC about whether it is time to legalise cannabis.
And when James asked him if he had taken the drug, Mr Khan surprised him. “I have,” said the Mayor, “in Amsterdam a long, long time ago when I was a lot younger.
“I was young once and I’m not a prude. And I did inhale as well.”
Met commissioner Dame Cressida Dick has said in the past that cannabis possession is “not the highest priority crime”.
The Met uses a “three strikes” rule of a warning, then a fine, with arrest a last resort.
The number of offences recorded by the Metropolitan Police for cannabis possession has been declining every year to 28,358 in 2017-18, and to 672 in the same year for possession with intent to supply.
UK law on cannabis provides for prison sentences of up to five years for possession and up to 14 years for supply and production.
Recreational use is legal in Canada, Uruguay and in 11 US states, and is decriminalised in a further 15 countries.
In the UK in 2016/17, black people were almost nine times as likely as white people to be stopped and searched for drugs, and were also more likely to be arrested and prosecuted.
According to figures from the Office for National Statistics, drug-related deaths in England and Wales are at a record level, with 2019 seeing the highest number in more than a quarter of a century.
Sadiq’s rival Shaun Bailey last year called for big companies to carry out random drug tests on their staff.
The Conservative London mayor candidate said the aim of mandatory drugs tests on staff would not be to get people fired, but to change the culture around drug use.
People who buy drugs are “funding the criminals who…unleash mayhem” on London’s streets, he argued.
He said the idea needed to take “human condition” into account, saying: “I know some people would absolutely fly if you gave them a lump sum to deal with every week.
“I know some people who would buy lots of drugs.”