Opponents of the proposed Northern Gateway pipeline are organizing what they're calling the largest act of peaceful civil disobedience on the oil sands issue in Canada.

Greenpeace Canada says a mass sit-in planned for the front lawn of the B.C. legislature in Victoria on Oct. 22 is backed by more than 80 leaders from the business, First Nations, environmental, labour and academic communities across Canada.

The group says those supporters include environmentalist David Suzuki, former Canadian UN ambassador Stephen Lewis, Council of Canadians chair Maude Barlow, lawyer Clayton Ruby, author Naomi Klein and economist Mark Jaccard.

Barlow says the protest is aimed at showing that attempts to gut Canada's environmental laws and put a price tag on the B.C. coast can't been done without a public response.

Environmentalist Tzeporah Berman says the risk of oil spills from Alberta to B.C. is too great.

The sit-in is aimed building on similar protests last year, including one in Ottawa in September and another in Washington D.C. in August that opposed the Keystone XL pipeline.