Environmentalists in Montreal convinced dozens of consumers to open their grocery bags on Sunday as part of an "attack on plastic" that aims to reduce excess packaging.

Activists gathered outside an east-end grocery store, where they offered to unwrap customers' purchases and put them in re-usable containers.

Sunday's event was inspired by the "Plastik attack" movement that originated in Bristol, England, and has led to similar events elsewhere in the world.

Co-organizer Caroline Thibault said the goal of the event was to encourage stores to reconsider the amount of packaging they use.

"These are individual choices, but I think that just by talking about it positively, people realize that it's a matter of common sense," she said.

"They tell themselves, 'Indeed, my pepper doesn't need to be wrapped in plastic film."

An hour after the event began, shopping baskets outside the store began to fill up with discarded packaging from produce, cookies and cereal.

The gathering took place outside a Provigo in the Rosemont neighbourhood, which agreed to the event.

Thibault said similar events are being planned in cities around the world including London, Paris and Geneva.