NDP joins several First Nations and municipalities that have filed legal challenges against the project, which would triple the capacity of the Alberta-to-BC pipeline and increase the number of tankers in Vancouver-area waters.

British Columbia says it will join the legal fight against Canada’s Trans Mountain pipeline expansion, while warning the company it can't begin work on public land until it gets final approval from the province.

The NDP government has hired former judge Thomas Berger to provide legal advice as it seeks intervener status in court challenges against Ottawa's approval of the $7.4-billion project.

Premier John Horgan promised in the provincial election this spring to use "every tool in the toolbox" to stop the expansion by Trans Mountain, a subsidiary of Kinder Morgan Canada.

Several First Nations and municipalities have filed legal challenges against the project, which would triple the capacity of the Alberta-to-BC pipeline and increase the number of tankers in Vancouver-area waters.

Environment Minister George Heyman said the expansion is not in the province's best interests. “A seven-fold increase in tanker traffic in BC's coastal waters is simply too great a risk to our environment, our economy and to thousands of existing jobs," he said.

BC's former Liberal government issued an environmental certificate for the project earlier this year.

Trans Mountain has said construction is set to begin in September, but Heyman said only three of eight environmental management plans required by the province have been accepted. The other five management plans have not been accepted because the company didn't adequately consult First Nations, Heyman said.

Kinder Morgan Canada president Ian Anderson said the company takes the comments of the BC government seriously and will meet with it to work through its concerns.

Fifty-one First Nations have signed mutual benefit agreements with Trans Mountain. Heyman said some do not necessarily favour the pipeline but want to ensure their people benefit if it proceeds.

Attorney General David Eby said the legal challenges against Ottawa's approval are expected to be heard this fall.

The Canadian Association of Oilwell Drilling Contractors condemned the province's position and called on Ottawa to prevent BC from "holding the jobs and livelihoods of thousands of Canadians and British Columbians hostage."