Environmental groups attacked a proposed pipeline from Canada's oil sands to the Pacific coast on Tuesday, saying it would attract tanker shipping and risk oil spills along a pristine coastline.

A report by the Natural Resources Defense Council, the Pembina Institute and the Living Oceans Society said the project posed risks to communities, salmon-bearing rivers, and coastal ecosystems, including the habitat of a rare white bear.

"The Northern Gateway pipeline is not worth the risk for the communities, rivers and Pacific coastline of British Columbia," said Nathan Lemphers, a policy analyst with the Pembina Institute.

The pipeline, proposed by Canadian company Enbridge, would transport oil from Alberta's tar sands through nearly 1,200 kilometers (750 miles) of rugged mountain landscapes to Kitimat on British Columbia's northern coast, for eventual shipping to Asia.

Up to 220 supertankers each year would sip from it, the report estimated.

"History has shown that oil tankers come with oil spills. It is not a question of if, but when, a spill will happen," said Katie Terhune of the Living Oceans Society.