VANCOUVER - The British Columbia government has been ordered by the province's highest court to reconsider its environmental assessment certificate allowing the expansion of the Trans Mountain pipeline.

In challenges by the Squamish Nation and the City of Vancouver, the B.C. Court of Appeal ruled the province's approval of the certificate was based on the original report from the National Energy Board, which was later quashed by the Federal Court of Appeal.

After the National Energy Board reviewed the project for a second time, the federal government approved the pipeline expansion again.

The Appeal Court says in its decision released today that in light of changes to the original report of the energy board when it reconsidered the project, provincial approval also needs to be reconsidered.

B.C.'s former Liberal government approved the expansion with 37 conditions, while relying on an agreement with the energy board that would stand for a provincial environmental assessment.

The three-judge panel said in its unanimous decision that through no fault of the provincial government, what is now Canada's environmental assessment of the pipeline was not the same assessment used when B.C. approved its certificate.