Enbridge, Canada's largest pipeline company, said it had asked the National Energy Board (NEB) for a three-year extension to allow for greater legal and regulatory certainty while discussions are held with aboriginal communities.

The company also said it would reduce its own stake in the project to boost potential ownership by First Nation and Metis partners from 10 percent to 33 percent, and pledged to give aboriginal owners an equal voice on project governance.

"From the beginning, Northern Gateway should have done a better job of building relationships with First Nations and Metis communities, particularly on the west coast of British Columbia," said project president John Carruthers in a statement.

Canada's previous government approved Northern Gateway in 2013, imposing more than 200 conditions on its construction. But the plan has faced fierce opposition from environmentalists, aboriginal groups and communities along the pipeline route.

Numerous groups filed legal challenges to stall the project, which would carry oil sands crude from Alberta to a deepwater port in Kitimat, on British Columbia's Pacific coast.

The permit, meanwhile, is set to expire by the end of the year unless construction of the pipeline or the export terminal is started.

If the NEB grants the extension, it will have to be approved by Canadian Prime Minister Justin Trudeau's cabinet.

In April, Trudeau said he still opposed the pipeline, but declined to speculate whether a changed route would work.

Alexandre Deslongchamps, a spokesman for Canada's Natural Resources minister, said that all resource projects must be environmentally sustainable and noted the government was committed to regaining public trust on project reviews.

The slump in oil prices has hit Canada's economy, especially in the province of Alberta, and has increased pressure from some quarters to get pipelines built.

Enbridge shares closed up 37 Canadian cents at C$50.69 on the Toronto Stock Exchange on Friday.

(Additional reporting by Amrutha Gayathri in Bengaluru and David Ljunggren in Ottawa; Editing by Shounak Dasgupta and Diane Craft)

By Julie Gordon