VANCOUVER -- The National Energy Board has recommended that the federal government approve the contentious $6.8-billion Trans Mountain pipeline expansion with 157 conditions.

The federal regulator issued its long-awaited report Thursday on the project after a two-year debate that cost millions, galvanized aboriginal and environmental protests and prompted mass arrests.

A three-member review panel recommended Ottawa approve Kinder Morgan Canada's proposal to triple the capacity of the pipeline, which carries crude from oilsands near Edmonton to Burnaby, B.C.

But Kinder Morgan will first have to address 157 engineering, safety, environmental and emergency preparedness conditions, including holding $1.1 billion in liability coverage and detailing its plans to reduce and offset emissions.

The positive recommendation has cleared a major hurdle for the project, with Prime Minister Justin Trudeau's cabinet set to make a final decision by the end of the year.

There was fierce opposition to the project and the process throughout the energy board's hearing, with the British Columbia government and cities of Vancouver and Burnaby opposing the expansion.

The board said its decision was based on a thorough scientific and technical examination.

"Taking into account all the evidence, considering all relevant factors, and given that there are considerable benefits nationally, regionally and to some degree locally, the board found that the benefits of the project would outweigh the residual burdens," the board said in a statement.

On Tuesday, the federal government announced details of an additional review on the pipeline. It appointed a three-member panel to conduct an environmental review of the project.

It will provide a report in November to Natural Resources Minister Jim Carr, who said the panel cannot override the energy board's decision but will consult, particularly with Aboriginal Peoples, "to see what the NEB might have missed."

The company's plan would add about 980 kilometres of new pipeline and reactivate about 190 kilometres of existing pipeline. The Westridge Marine Terminal beside Burrard Inlet off Burnaby would also be expanded.

Environmentalists demonstrated against the Trans Mountain project, including more than 100 people who were arrested and charged with civil contempt in the fall of 2014. Most of the charges were later dropped.