Queensland government moves to give cannabis the same status as heroin and cocaine as the most dangerous drugs will push marijuana users onto harder drugs, according to a visiting Canadian advocate.

Dana Larsen, who operates cannabis dispensaries in Vancouver, will give a public talk on Sunday about Canada's new Prime Minister Justin Trudeau's plans to legalise and regulate cannabis use.

Cannabis.

Mr Larsen said Queensland's move to equate cannabis with heroin, ecstasy and cocaine would push marijana users onto harder drugs.

"I'm all for harm reduction," he said. "I know a lot of people who use cannabis to stay off heroin, methadone and alcohol. Cannabis is a safer alternative."