MONTREAL -- By the end of the year, shoppers in Montreal will no longer be able to get a plastic bag in a retail store.

On Twitter and Facebook Wednesday morning, Mayor Valerie Plante announced that the city will ban all plastic bags, saying that they can take 1,000 years to fully decompose, and that the city "can't wait 1,000 years" to truly tackle the global plastic crisis.

"We have to reduce at the source, and that happens with behaviour changes," Plante said.

Montreal, like many municipalities in the region, already bans the commercial use of single-use plastic bags. It hasn't had the desired effect, though, the city said, because many retailers moved to slightly thicker plactic bags, and ultimately didn't change the habits of shoppers.

On Wednesday morning, Plante asked city manager Serge Lamontagne to formally expand the ban to include all plastic bags used in retail stores in Montreal, citing a recent study proving plastic pollution is harmful.

Executive committee member Laurence Lavigne Lalonde said it comes after the city's waste management plan was well received.

"We decided that the priority was to reduce the waste material that we generate here on the territory of Montreal. We don't want to only take the plastic and recycle, we need to reduce what we generate, what we produce, on the territory of Montreal, because it's really harmful to our environment," she said.

Plante also encouraged other Quebec municipalities to follow suit and implement similar bans.

The city said it was also looking into restrictions on other single plastics, including bottles, plastic cutlery and straws, but hasn't yet made any announcement to that effect.

A national ban on many single-use plastics is on track for 2021.