The Canadian government approved the $12 billion Bay du Nord project in April, after an environmental assessment concluded it would not cause significant adverse effects.

The project involves building a floating platform to drill an estimated resource of up to 1 billion barrels in the Atlantic Ocean, about 500 km (310 miles) off the coast of Canada's Newfoundland and Labrador province.

Environmental groups slammed the approval and Sierra Club and Équiterre, represented by Ecojustice, filed a lawsuit on May 6 seeking to overturn the decision.

Sierra Club spokeswoman Gretchen Fitzgerald said the lawsuit argues that federal Environment Minister Steven Guilbeault failed in his duty to consider the international impact of climate-warming carbon emissions generated by Bay du Nord.

"Approving a new oil project that will emit that much greenhouse gas emissions and contributes to the climate emergency will certainly go beyond international boundaries," Fitzgerald said.

Earlier on Wednesday she addressed shareholders at Equinor's annual general meeting in Stavanger, Norway, urging them to cancel the project.

Equinor said it is focused on working with partners and local authorities to mature the project towards a final investment decision. Canada's Cenovus Energy holds a 35% stake in Bay du Nord.

"We strongly believe that this can be an important project with high value creation, a low carbon footprint and strong economic value for the region," an Equinor spokesperson said.

Canada is the world's fourth-largest crude producer and Prime Minister Justin Trudeau's Liberal government is favouring oil projects with lower carbon emissions per barrel to help meet its climate targets. Equinor says Bay du Nord will be the lowest carbon-intensity oil project in Canada.

(Additional reporting by Nerijus Adomaitis in Oslo; Editing by Marguerita Choy)

By Nia Williams