(Adds comments, environmental protest, details, background))
By Julie Gordon
VANCOUVER, Jan 6 (Reuters) - Canadian Prime Minister Stephen Harper said on Monday he was confident that TransCanada Corp's controversial Keystone XL pipeline would be eventually approved by U.S. authorities.
U.S. President Barack Obama is set this year to decide the fate of the northern leg of the proposed project, which would carry crude from the Alberta oil sands in Canada to the U.S. Gulf Coast. Obama is under heavy pressure from environmental activists to block the pipeline.
"I am confident that in due course - I can't put a timeline on it - the project will one way or another proceed," Harper said during a question-and-answer session at the Vancouver Board of Trade.
The event was disrupted when two climate protesters walked onto the stage and held up signs as they stood next to Harper. One of the placards said "Climate justice now."
Green groups say building the pipeline will speed up extraction of oil from the tar sands - a process that consumes more energy than regular drilling.
Harper's chief spokesman declined to comment on the security breach.
Canada's right-leaning Conservative government strongly backs the pipeline and Harper repeated his view that he hoped Washington would approve it, given what he said was the strong support for the project among American politicians and the general U.S. population.
The timeline for U.S. approval has slipped repeatedly and Harper said Obama had "punted" the decision.
In September, Harper told a New York audience that the logic behind the pipeline was "simply overwhelming" and said "you don't take no for an answer." The 1,200-mile (1,900-km) pipeline would carry 830,000 barrels a day.
Environmentalists and aboriginal groups are also strongly opposed to Enbridge Corp's proposed Northern Gateway pipeline from the oil sands to the British Columbia coast and from there to Asian markets.
The government backs the idea of more pipeline capacity to the Pacific coast on the grounds that Canada needs to reduce reliance on the United States, which takes around 99 percent of Canadian energy exports.
Late last month a review panel recommended the pipeline be built. Ottawa has until the middle of June to make a decision.
"We will not approve projects unless they're not only in our economic interest but also they meet the highest standards of environmental protection," said Harper.
Opponents of the Northern Gateway - part of which would run across aboriginal lands as well as crossing remote areas - say a breach would cause an environmental catastrophe.
A group of about 20 anti-pipeline protesters gathered outside the Vancouver hotel where the event took place, beating drums and chanting "We don't want your dirty oil."
Harper also said he was more optimistic about the economy in 2014 than in past years because of evidence of stronger growth in the United States and a comeback in Europe.