As the federal government says it's willing to have Indigenous investment in the Trans Mountain expansion, B.C. Indigenous groups say they will continue to oppose the contentious project.

The Liberal government says it's requiring another round of consultation with Indigenous communities affected by the $4.5 billion project, and will see if they want to become economic partners in the venture.

Prime Minister Justin Trudeau says the government is willing to consider selling as much as a 100 per cent stake in the project to Indigenous investors.

The original approval for the project was torn apart by the Federal Court of Appeal last summer, citing incomplete Indigenous consultations and a faulty environmental review.

The Union of B.C. Indian Chiefs issued a statement Tuesday blasting Ottawa's decision to approve the controversial project for a second time.

"Today's announcement demonstrates a lackadaisical and irresponsible approach to combatting climate change and recognizing the human rights of Indigenous Peoples," the organization said in a press release.

Grand Chief Stewart Phillip took the opposition a step further, saying the group would continue to actively resist the project.

"Our lands are burning and flooding. Our fish are dying and our people are suffering. Now is not the time to recklessly pursue environmentally devastating projects while our territories suffer," he said in a statement.

The Tsleil-Waututh Nation says it also remains opposed to the project and will appeal the approval, saying their concerns were unaddressed by the federal government.

"We believe the consultation once again missed the mark set by the Supreme Court of Canada and will defend our rights," said Chief Leah George-Wilson.

George-Wilson says their concerns centre on the risks and impacts of oil spills, the project's impact on killer whales and the risk to Tsleil-Waututh's rights and titles.

The nation also claims the project is "uneconomic."

"The independent cost benefit analysis of the project, consistent with Canadian government benefit cost guidelines, finds the Trans Mountain Expansion Project results in a loss to Canada of $11.8 billion."

Will George, an Indigenous activist who crashed a fundraiser luncheon held for the prime minister held in Vancouver in early June, said he and his group Protect the Inlet would continue to oppose the project.

"No matter who approves it, this pipeline will not be built," he said in a release.

Indigenous opposition may also receive support from the provincial government, with Premier John Horgan saying the province would consider joining First Nations lawsuits against the project.

"If the federal government sees themselves back in court, whether it's the Tsleil-Waututh, the Squamish or others, we'll certainly take a good hard look at that and if it's in the interest of British Columbia to join them, we will," he said.

But not all Indigenous groups are against the project.

Project Reconciliation, a group comprised of First Nations leaders from Saskatchewan to B.C., is pitching more than 300 First Nations and Indigenous communities on investing in the pipeline.

"For many decades a lot of First Nations have been a part of the oil and gas industry and this opportunity to buy the Trans Mountain pipeline is a one-time opportunity and we're hoping to make the best of it," B.C. director Shane Gottfriedson said at a pro-pipeline rally in downtown Vancouver Tuesday.

With files from the Canadian Press