First Nations representatives marched through downtown Vancouver Thursday in protest against a proposed oil pipeline. (CBC)Native leaders are vowing to do whatever it takes — including civil disobedience — to block a proposed oil pipeline across northern B.C.

Representatives of 61 First Nations marched and drummed through downtown Vancouver streets Thursday to Enbridge Inc.'s headquarters to deliver a signed declaration stating their opposition.

"Civil disobedience is not out of the question," said Larry Nooski, from the Nadleh Whut'en First Nation near Fraser Lake.

The $5.5-billion Northern Gateway Pipeline proposed by Enbridge would run from the Alberta oilsands to B.C.'s North Coast.

Signatories of the declaration say the twin pipelines that would run 1,170 kilometres from an oilsands hub near Edmonton to the port community of Kitimat would pose the risk of an oil spill either along the pipelines or from tanker traffic along the Pacific coast.

Although the group believes they have the legal capacity to halt the project, Enbridge said the ultimate decision does not rest with First Nations.

"A joint review panel made up of the National Energy Board and the Canadian Environmental Assessment Agency will make the final decision," said company spokeswoman Gina Jordan.

The panel is holding a public regulatory review process that is engaging aboriginal groups and citizens in the decision making, said Jordan.

She said Enbridge has signed a protocol with 30 First Nations groups, although she declined to release their names, citing confidentiality. She did say all of them are either located along the route of the proposed pipeline or nearby.

Two Enbridge pipeline leaks

An April 2009 publication by Enbridge features a picture of then chief Robert Charlie, of the Ts'il Kaz Koh First Nation, better known as the Burns Lake Band, during the signing of a protocol agreement for the Northern Gateway in December 2008.

Charlie has since been replaced in an election, and it is not known whether the change in leadership will affect the protocol agreement. Current Chief Albert Gerow could not be reached for comment.

Enbridge has been under fire in recent months for two high-profile pipeline leaks in the U.S. Midwest.

In July, a pipeline in southern Michigan spilled millions of litres of crude into the Kalamazoo River, and less than two months later, another line leaked in the Chicago area.

Calling themselves the Save the Fraser Gathering of Nations, the aboriginal groups took out a full-page ad in Thursday's Globe and Mail newspaper to declare that they will not allow Enbridge to transport tar sands oil across their lands and watersheds.

"An oil spill in our lands and rivers would destroy our fish, poison our water and devastate our people, our livelihoods and our futures," said the ad.

"We will protect our rivers from Enbridge oil."