Two First Nations in northwest British Columbia are suing the federal government to quash its approval of the Ksi Lisims floating liquefied natural gas (LNG) facility near Prince Rupert.

The Lax Kw'alaams Band and the Metlakatla First Nation filed separate judicial reviews in Federal Court earlier this month, alleging that the Minister of Environment and Climate Change ignored their concerns about the project's adverse impacts.

The suit follows the federal approval announced last month by the Impact Assessment Agency of Canada, just hours after B.C. issued its own approval of the project and planned pipelines transporting LNG to the proposed floating facility. 

Federal Energy Minister Tim Hodgson praised the decision as an example of the "one project, one review" system, which relied on the province's assessment.

However, the Metlakatla First Nation argues that the approval relied on "speculative economic concepts" to justify the project, while ignoring "mounting evidence" that it is not economically feasible.

The Lax Kw'alaams Band states the facility is in its traditional territory and threatens to displace its Aboriginal rights and title "in perpetuity."

Both nations also have outstanding Aboriginal title claims in the B.C. Supreme Court for the Mylor Peninsula, where a transmission line is required to power the facility.

The Ksi Lisims project involves two floating facilities designed to export 12 million tonnes of LNG annually. It is a partnership between the Nisga'a Nation, Rockies LNG Limited Partnership, and Western LNG, which is based in Houston, Texas.

Meanwhile, the government and the Ksi Lisims project team have not yet responded to the claims in court. The project also faces separate legal challenges filed in September, which claim the approval for its supply pipeline, the Prince Rupert Gas Transmission line, should have expired.