VANCOUVER - The City of Vancouver said on Monday it had taken legal action against the Canadian energy regulator's approval of Kinder Morgan's Trans Mountain pipeline expansion, which would increase the number of oil tankers passing through city waters.

In a statement posted on the city's website, Mayor Gregor Robertson called the review by the National Energy Board (NEB) "flawed and biased" and said that it ignored scientific evidence on the consequences of a major oil spill and the impact of greenhouse gas emissions.

The city has filed an application for judicial review in an effort to quash the NEB's decision last month to recommend the approval of Kinder Morgan plans to twin the existing pipeline that carries crude from Alberta to a port in Metro Vancouver.

The regulator said it found the $6.8 billion project, which would boost capacity from 300,000 barrels per day to 890,000 bpd and the number of oil tankers in Vancouver waters nearly seven-fold, would not cause significant harm to the environment.

But critics, who say the project will hasten the development of Alberta's oil sands and worry about the impact of an oil spill on Canada's west coast, were quick to pledge action against the regulator's decision.

The Squamish First Nation, whose traditional territories include areas directly impacted by the pipeline and shipping routes, filed an application for judicial review late last week.

The NEB's recommendation must still be reviewed by Prime Minister Justin Trudeau's cabinet, with a final decision expected in December.