VANCOUVER -- Prime Minister Stephen Harper's government has been somewhat unabashed in supporting the Northern Gateway project that would see a pipeline deliver crude from the Alberta oilsands to a port on the B.C. coast.

But Harper said Tuesday, science, not politics, will decide the fate of a controversial pipeline proposed by Calgary-based Enbridge.

"In a broad sense, without getting into the specifics of any project. . . we think it's obviously in the vital interests of Canada and in the vital interests of British Columbia," Harper said following an announcement in Vancouver.

"As Canada's Asia-Pacific gateway, the economic growth we expect to have here in the future is going to be based on commerce with the Asia-Pacific region and we think it's important that we continue to diversify our exports through this province."

But Harper rejected any suggestion that the $6-billion project is a done deal as far as his Conservative government is concerned.

"I've been very clear that decisions on these kinds of projects are made through an independent evaluation conducted by scientists into the economic costs and risks that are associated with the project, and that's how we conduct our business," Harper told reporters.

He said his government has already invested in environment surveillance and mitigation of environmental risk, and will make further investments in the future, though he offered no specifics and took only a few questions from the contingent of media waiting to question the prime minister on the pipeline issue.

"I think that's the only way that government can handle controversial projects of this manner, is to ensure that things are evaluated on an independent basis, scientifically, and not simply on political criteria."

Ottawa wants to see B.C.'s export trade grow and diversity, he said, but the proposal will be evaluated on its own merits.

But Peter Julian, the Opposition New Democrats' natural resources critic, said nothing could be further from the truth.

"Here's a government that has gutted the environmental assessment process and the (National Energy Board) process, so that politics trump science, trying to tell British Columbians that well, in fact, science will play a bigger role than politics. It's clearly not the case," Julian said.

Under the revamped environmental assessment process, a government decree in favour of the project is inevitable, Julian said.

This is the same government that in the last budget cut Environment Canada's Environmental Emergencies Program office in British Columbia, which co-ordinates the clean-up of oil spills in federal jurisdiction including the offshore, he said.

Harper is simply trying to assuage British Columbian voters, who Julian believes are overwhelmingly opposed to the project.

"What we have is a federal government that, though it's using soft words out here in B.C., is doing everything it can to try to ram it down the throats of British Columbians and I don't believe that will work," he said.

The proposal by Enbridge would see twin pipelines deliver diluted bitumen over 1,170 kilometres from the oilsands in northern Alberta to a terminal to be built for tankers near Kitimat, B.C.

The federal environmental review process got underway in January, and last week Ottawa set a Dec. 31, 2013 deadline for the assessment to be complete.

The process ignited tensions over the project that grew worse last month when the U.S. National Transportation Safety Board criticized Enbridge's response to the spill of millions of litres of oil into Michigan's Kalamazoo River on July 25, 2010, affecting more than 50 kilometres of waterways and wetlands.

Shortly after the damning report, Enbridge announced it would invest another $500 million in safety improvements to the Northern Gateway pipeline but the Canadian pipeline giant continues to see opposition to its proposal.

Many aboriginal groups in B.C. have vowed to fight Northern Gateway, and next week, delegates at the United Church of Canada general council meeting in Ottawa will debate a resolution calling on the church to reject construction of the proposal.

Even the provincial government ended its neutral stance on the project, demanding strict environmental protections and a greater share of royalties.

Harper said he has spoken to B.C. Premier Christy Clark about the issue, but that was all he would say.

"I'm not going to obviously share with you any private conversations I've had with any premier, and I have discussed this with the premier of British Columbia and other premiers," he said in response to questions about Clark.

"I'm not going to get into an argument or a discussion about how we divide hypothetical revenues."