Greenpeace protesters created a mock pipeline oil spill outside the Vancouver offices of Enbridge on Wednesday morning. (Robert Zimmerman/CBC)

Greenpeace protesters staged a mock oil spill Wednesday morning at the downtown Vancouver offices of Enbridge after the Alberta pipeline company admitted responsibility for the oil leak now going on in Michigan.

Four protesters occupied the company's offices in a downtown tower on Burrard Street, while about a dozen others used a section of pipeline mounted on a truck to stage the mock oil spill outside.

The protesters poured a mixture of molasses and water over an image of the B.C. coastline in an attempt to draw attention to an Enbridge proposal to build a 1,000-kilometre pipeline from the Alberta oilsands to B.C.'s West Coast region.

A security guard in the Enbridge office said most of the staff had gone home for the day and nobody was available to comment. The employees vacated the office after the protesters used oil tar from the Gulf of Mexico spill to write a slogan on the glass doors.

"Enbridge is poised to become the BP of B.C.," Greenpeace B.C. director Stephanie Goodwin said in a statement released by the group.

The proposed Northern Gateway pipeline has generated opposition from First Nations and environmental groups, who fear a spill could jeopardize the local environment.

"If Enbridge's Northern Gateway Pipelines project goes ahead, it's not a question of if a spill will happen but when, where and how large," Goodwin said.

The Enbridge pipeline would carry about 525,000 barrels of crude a day to a container terminal in Kitimat, B.C., where about 200 oil tanker ships would be filled each year.

First Nations oppose pipeline

Meanwhile, aboriginal leaders say the spill in southern Michigan is further evidence that B.C. should steer clear of such projects.

Art Sterritt, the Coastal First Nations executive director, said that despite Enbridge's claim that the Northern Gateway project will be a model of safety, such a spill could happen in B.C.

Sterritt, who recently visited the U.S. Gulf Coast to view the effects of the oil spill there, said he was told by local people the only way to avoid a similar disaster is to keep oil out.

Coastal First Nations president Gerald Amos said a spill on the B.C. coast would wipe out the marine resources that First Nations depend on heavily.

New route for Alberta oil

A second arm of the pipeline would carry about 193,000 barrels a day of condensate, which is used to thin the crude oil during transportation, back to Alberta.

The company says the project will generate hundreds of jobs in the region and provide an important new route to sell Alberta oil to expanding Asian countries.

On Tuesday, the company said its pipeline carrying oil from Griffith, Ind., to Sarnia, Ont., has leaked more than three million litres of oil into Battle Creek in southwestern Michigan.

The spill has endangered birds and other wildlife in and around the creek as well as in the Kalamazoo River, a major waterway fed by the creek and emptying into Lake Michigan.

The leak in the 76-centimetre, 41-year-old pipeline was first detected Monday morning but not reported to federal authorities until the afternoon, U.S. officials said.

With files from The Canadian Press