Prime Minister Justin Trudeau has called for a moratorium on crude oil tanker traffic for B.C.'s North Coast.

Trudeau outlined the directive in a mandate letter to Canada's transport minister, Marc Garneau, on Friday. In it, he asked Garneau to formalize the agreement with three other ministries: fisheries, natural resources and environment.

It's unclear what impact a moratorium would have on Enbridge's Northern Gateway pipeline, which would carry bitumen from Alberta to Kitimat, B.C. The project was approved in June 2014 with 209 conditions.

"This ban ends the dangerous Northern Gateway pipeline proposal," said Karen Mahon, from ForestEthics, an environmental group that advocates for the protection of B.C.'s coast. "Without tankers, crude oil has no place to go, that means no pipelines, no oil trains moving tarsands to the northern B.C. coast."

Enbridge said in a statement that despite the mandate for a moratorium on tanker traffic, it is confident the federal government will consult with 26 of 45 First Nations that have signed on with the project about what impact a tanker ban could have on them and also a perceived economic boost for Western Canada.

Enbridge describe the Northern Gateway project as having "one of the most exhaustive reviews of its kind in Canadian history."

"We have made significant process building support on the B.C. coast and along the pipeline corridor," said spokesman Ivan Giesbrecht.

"Along with the project's aboriginal equity partners, we are looking forward to an opportunity to sit down with the new prime minister and his cabinet to provide an update on the progress of our project and our partnerships with First Nations and Métis people in Alberta and B.C."

Still, Enbridge says the earliest the pipeline could be built is 2019, prompting some analysts to question whether the company is fully committed to the project given the obstacles it still faces.

The moratorium would require legislation and would no doubt prompt debate in the House of Commons.

The mandate letter from Trudeau comes a week after U.S. President Barack Obama rejected TransCanada's proposed Keystone XL pipeline, saying it did not serve his country's national interests.

Both Trudeau and Obama will be part of the G20 meeting in Antalya, Turkey, this weekend and the United Nations climate change conference in Paris starting on Nov. 30

Also on Friday, Trudeau asked his minister of fisheries and oceans to re-open the Kitsilano Coast Guard station in Vancouver.

With files from the CBC's Betsy Trumpener