Canada’s Liberal government will introduce legislation to decriminalise and regulate recreational marijuana in spring 2017, according to the health minister, Jane Philpott.

The prime minister, Justin Trudeau, promised during last year’s election campaign that his government would legalise recreational marijuana, following the US states of Washington and Colorado, but the time frame has been unclear.

Philpott, speaking on Wednesday at a special session of the UN general assembly in New York on drug problems around the world, said the Canadian law will ensure marijuana is kept away from children and will keep criminals from profiting from its sale.

“We will work with law enforcement partners to encourage appropriate and proportionate criminal justice measures,” she said. “We know it is impossible to arrest our way out of this problem.“

Former Toronto police chief Bill Blair, the government’s point man on legalisation, has emphasised that current laws that make marijuana illegal remain in effect.

Medical marijuana is a separate issue from recreational marijuana in Canada and is already legal. Canada’s medical marijuana growers say a jump in the number of illegal marijuana dispensaries as the federal government decides how to regulate the drug is costing them customers.

Medical marijuana patients in Canada are set to regain the right to grow their own cannabis after a federal court judge in March struck down the ban introduced by the previous Conservative government.