Canadian Prime Minister Justin Trudeau's government introduced legislation on Thursday to let adults possess 30 grams of marijuana in public - a measure that would make Canada the largest developed country to end a nationwide prohibition on recreational marijuana.

Trudeau has long promised to legalise recreational pot use and sales. U.S voters in California, Massachusetts, Maine and Nevada voted last year to approve the use of recreational marijuana, joining Colorado, Washington, Oregon and Alaska.

The South American nation of Uruguay is the only nation to legalise recreational pot.

The proposed law allows four plants to be grown at home. Those under 18 found with small amounts of marijuana would not face criminal charges.