May 12 (Reuters) - Canada’s Liberal government has introduced legislation for a moratorium on oil tanker traffic along the northern coast of the British Columbia province, the country’s transport department said on Friday, delivering on an election promise.

Canadian Prime Minister Justin Trudeau ordered the ban soon after the election in 2015, in which he took power on a pledge to balance resource development with protecting the environment.

Friday’s bill will likely pass because Trudeau’s Liberals hold a majority in Parliament.

Trudeau’s orders for the ban effectively slammed the door on Enbridge Inc’s Northern Gateway pipeline, a project facing massive development hurdles that was to deliver oil to the north coast for export via tankers.

The move is part of a Liberal plan to toughen response to oil spills at sea. The plan was announced last year days before Trudeau formally rejected Northern Gateway, but approved another pipeline project through British Columbia, Kinder Morgan Inc’s Trans Mountain expansion.

According to Transport Canada, vessels carrying less than 12,500 metric tonnes of crude or other oils will be exempt from the tanker ban, so as to ensure northern communities can receive shipments of heating oils and other products.

“The legislation proposes strong penalty provisions for contravention that could reach up to C$5 million ($3.65 million),” according to the department.

The ban does not apply to the south coast, which will likely see increased tanker traffic if Trans Mountain goes online.

Whether that happens according to schedule, however, has become uncertain after British Columbia’s pro-energy Liberals, unaffiliated with Trudeau’s federal party, lost their majority in a provincial election on Tuesday.

While absentee ballots still need to be counted in the close race, if the current seat count in the provincial legislature holds, the future of key energy projects in British Columbia will be pitted against the ability of the Liberals to work with the third-party Greens.