Canada’s National Energy Board (NEB) has approved the construction of a large portion of the Trans Mountain pipeline expansion project, despite concerns from environmental groups.

The NEB said that all relevant conditions had been met and the construction of segments one to four of the oil pipeline will go ahead. These sections run from Edmonton, Alberta to Kamloops, British Columbia, covering a distance of around 352 miles.

While Canadian Prime Minister Justin Trudeau has announced his support, the project has been criticised by environmentalists.

In a recent Ipsos poll commissioned by Global News, 56% of respondents said they supported the pipeline expansion, with 24% opposing the project. Around 20% of Canadians said they were undecided.

Oil pipeline transportation company Kinder Morgan Canada announced it would sell the project to the government last May, in a deal expected to be worth C$4.5bn.

Last month, five activists with Greenpeace Canada climbed Montreal’s Olympic tower to protest the pipeline expansion.

Greenpeace spokesperson Loujain Kurdi said in a press release: “The courage of these activists gives a voice to Quebecers and people around the world who do not want new pipelines built in their name or with their money.

“With C$4.5bn Justin Trudeau could install 3 million electric charging stations. For roughly $ 3.2 billion, he could ensure that every Indigenous community in Canada has access to clean water. Surely that would be money well spent, as would investing in renewable energy to accelerate the transition to a sustainable economy.”

Concerns have also been highlighted that the pipeline project may cost more than the original total budget of C$7.4bn ($5.6bn). The project could also take longer to complete than its estimated in-service date of December 2020.

Kinder Morgan Canada announced that preliminary works had begun in Alberta. Pipeline construction crews will arrive at the site in spring 2019, but there is no information on the estimated completion date.

Advocates of the construction have stated that it will benefit Canadian oil producers who are struggling to transport crude to market.

The discount on the nation’s crude oil reached a five-year high in August, resulting from increased production that current pipeline infrastructure cannot support.

The Trans Mountain expansion, which would nearly triple the transport capacity to 890,000 barrels per day, is one of three large export pipeline projects undertaken in Canada.

The Westridge Marine Terminal expansion is already under construction, and preliminary works have started at Kinder Morgan’s terminal and tank farm nearby.

According to the NEB, 72% of the detailed final route for the Trans Mountain pipeline expansion had been approved. Consent hearings for the remaining segment will be held in October.