"Projects like this are subject to independent evaluation that will look at these kinds of issues - environmental and safety and security issues," Mr. Harper said. "I think the reality for anybody who looks at this business is that the absolute safest way to transport energy products is through pipelines, that is the safest way you can go."
The Transportation Safety Board is investigating the Lac-Megantic disaster and has raised concerns about whether the train with its 72 cars of crude from North Dakota's Bakken fields was particularly dangerous, given what officials described as a surprisingly devastating fireball from the explosion.
With oil production in North America booming, the industry needs both new pipeline capacity and more rail cars to get its crude oil to markets. But environmental critics say both modes entail risks of accidents and spills.
TransCanada announced on Thursday that it plans to build a $12-billion pipeline to bring 1.1 million barrels per day of Western oil to refineries and marine export terminals in Quebec and Saint John, N.B., subject to regulatory approval. The company will convert existing natural-gas pipeline into oil use through the Prairies and Ontario, and build a new line through Quebec and New Brunswick.
Asked about the Energy East project on Friday, Mr. Harper endorsed the concept of a cross-Canada pipeline, but said he could not speak to the specific project, which will be subject to a full assessment by the National Energy Board.
"We need to sell our energy products, but it is a good idea that we find pan-Canadian solutions so that all of this country benefits from our energy products and we enhance energy security. So in principle, I think projects like this are a good idea, but they'll be subject to rigorous independent analysis."
In making the announcement, the company's chief executive, Russ Girling, acknowledged that people in Quebec will be particularly sensitive to the risks, and vowed to do "everything we can possibly do" to ensure such events don't happen in the future.
Quebec City Mayor Regis Labeaume, who joined the Prime Minister for an announcement, said he favours crude pipelines and that "the fewer trains, the better." The port of Quebec currently handles tanker traffic bringing imported crude for refineries in that city and Montreal, and would be an export terminal for Western oil producers under the TransCanada plan.
NDP energy critic Peter Julian said his party also supports the idea of a west-to-east pipeline, but said the Harper government has undermined public confidence by gutting the environmental review process.
At his news conference, the Prime Minister also defended TransCanada's proposed Keystone XL project against an assertion from U.S. President Barack Obama that its job-creation impact has been overblown. Mr. Obama is expected to decide late this year whether to approve the pipeline, which environmentalists have condemned.
"Our number one priority in Canada is the creation of jobs and clearly this is a project that will create jobs on both sides of the border," Mr. Harper said. "And it is in our judgment an important project not just for our economy and job creation, but for the long-term energy security of North America."