Prime Minister Justin Trudeau sparked anger and condemnation in Alberta on Friday when he said at a town hall in Ontario that the oil-sands industry needs to be “phased out” as the country transitions to a lower-carbon economy.

Meeting with people in Peterborough, Ont., Mr. Trudeau was asked about the government’s approval for oil-industry pipelines and how that decision was consistent with Canada’s pledge to dramatically reduce greenhouse-gas emissions. The oil sands sector remains one of the country’s fastest-growing sources of GHGs.

While he reiterated his government’s support for pipelines and insisted economic development goes hand in hand with environmental protection, the Liberal Prime Minister suggested the oil sands sector is essentially a sunset industry that the government would eventually wind down.

“We can’t shut down the oil sands tomorrow. We need to phase them out,” he said. “We need to manage the transition off our dependence on fossil fuels.”

In the wake of that comment, social media erupted in a torrent of outrage, with conservative politicians in Alberta fuelling the fire by posting a short clip of his offending comment that edited out his support for pipeline projects.

Mr. Trudeau – who will hold a cabinet retreat in Calgary in 10 days – has sought to woo Albertans and distance himself from the legacy of his father, Pierre, who was long reviled in the province over his interventionist national energy program. The Prime Minister has long supported pipeline projects, and his government recently approved two controversial pipeline expansions that will add a million barrels a day of export capacity for 40 or more years.

But opponents contend the Liberals’ climate-change agenda – with its costly regulations and carbon pricing – is a threat to the health of a high-cost oil sands industry. And they have recently contrasted Mr. Trudeau’s agenda with the plan by president-elect Donald Trump to cut taxes and regulatory burdens on the U.S. oil companies with whom Canadian operators compete for markets and investment.

“The verdict is in. Prime Minister Trudeau has confirmed Albertans’ worst fears about his Liberal government and its plans for our energy sector,” Wildrose Party Leader Brian Jean said in a release that included a link to a clip on Facebook of Mr. Trudeau’s statement.

“By vowing to ‘phase out’ the oil sands, Mr. Trudeau has declared his true feelings towards our province, and Western Canada as a whole.”

Former federal cabinet minister Jason Kenney, who is campaigning for the leadership of Alberta’s Progressive Conservative Party, said the Prime Minister is effectively calling for Canada to shut down its single greatest economic advantage.

A spokesman for the Prime Minister’s Office said Mr. Trudeau was reiterating a long-stated view – including by his Conservative Party predecessor Stephen Harper – that Canada needs to lessen its dependency on fossil fuels. Mr. Harper agreed at the G7 meeting in 2015 that the world needs to stop burning fossil fuels by the end of the century, though he later dismissed the statement as aspirational only.

“As a government, we were proud to work with provinces and territories to introduce a price on carbon pollution – to create jobs and protect the environment,” PMO spokesman Cameron Ahmad said in an e-mail. “We are also proud of our recent [pipeline] announcement, which will ensure that we can move Canada’s natural resources to international markets.”

Greenpeace Canada activist Keith Stewart said Mr. Trudeau was reflecting a global determination to end the use of fossil fuels which will, over time, eliminate demand for oil sands crude.

“The only real debate is how fast this will happen,” he said.

The federal government recently produced a long-term low-carbon strategy that laid out a broad plan to slash greenhouse gases by 2050. The document made no mention of phasing out or even reducing oil sands production, but instead pointed to technologies that could significantly reduce emissions from the sector.

The uproar from Mr. Trudeau’s political opponents on Friday was predictable. However, Alberta Premier Rachel Notley – who has become a key ally of the Prime Minister as he has moved to implement his climate-change strategy – released a video statement late Friday saying: “We’re not going anywhere, any time soon.”

The Premier said that oil and natural gas will help power the global economy for generations to come, “and our job is to make sure that Alberta’s product is the first in line. That’s why we’re working with industry to position Alberta as a global energy leader – the most progressive and sustainable producer of oil and gas anywhere in the world.”