Al Gore has thrown his support behind opponents of a contentious Canadian pipeline project and condemned the planned expansion as federal officials in Canada scramble to ensure it goes ahead.

“The Kinder Morgan pipeline carrying dirty tar sands oil would be a step backward in our efforts to solve the climate crisis,” Gore tweeted on Thursday.

He went on to say that he stands with John Horgan, the premier of British Columbia and Gregor Robertson, the mayor of Vancouver, as well as, “all of the Canadians – including the First Nations – who are fighting to stop this destructive pipeline.”

For months, Alberta and British Columbia have been locked in a standoff over plans, spearheaded by Texas-based Kinder Morgan, to expand an existing pipeline and lay nearly 1,000km of new pipe from Alberta’s oil sands to the Pacific coast.

The $7.4bn project, which still needs to obtain numerous local permits and approvals, would nearly triple the flow of Alberta’s landlocked bitumen to the west coast.

It has been bitterly opposed by some in British Columbia, who point to the impact that a dramatic rise in tanker traffic could have on the region’s southern resident killer whales, a population already on the knife-edge of extinction, as well as the province’s multibillion dollar tourism industry.

Others point to the existing pipeline’s track record; since 1961, the Trans Mountain pipeline has reported approximately 82 spills, with around 30% of those spills occurring along the pipeline’s route.

Efforts to stop the expansion have heated up in recent weeks, with thousands of people joining indigenous-led protests in British Columbia. More than 200 people have been arrested for blocking the entrance of a facility belonging to Trans Mountain, including two federal MPs.

The political stalemate over the project catapulted into the national conversation last month after Kinder Morgan Canada announced it was halting all non-essential spending on the project and planned to walk away unless it saw a clear path to completion by the end of May.

In response, Justin Trudeau said Canada’s government was prepared to use taxpayer dollars to push forward with the proposed plans. “The Trans Mountain expansion is a vital strategic interest to Canada – it will be built,” he told reporters.