Hundreds of British Columbians took to the streets of downtown Vancouver Tuesday night to protest the federal government’s approval of the Kinder Morgan pipeline expansion.

Environmentalists, First Nations, and politicians were among those who gathered in Library Square near West Georgia and Homer streets in opposition of the pipeline expansion.

“I feel so betrayed, because this prime minister and this government engendered such hope in us,” Vancouver City Councillor Adriane Carr told the crowd.

“And then he says we can approve two pipeline projects, Kinder Morgan and Line 3, and we can do climate change too. He’s either an idiot or he’s a liar.”

“Liar!” shouted the crowd, prompting a small child to yell “liar, liar pants on fire.”

Carleen Thomas, a member of the Tsleil-Waututh, says the Liberal government “sold us out.”

“They threw us under the bus. They threw us under the tank and this is not acceptable,” she said.

The protesters marched with banners and signs, singing and drumming through the streets of downtown Vancouver, ending outside the art gallery.

Prime Minister Justin Trudeau announced the project would be approved with 157 conditions at a news conference Tuesday. He said he expects the decision to be “bitterly disputed” by a number of people across the country, but said the project is in Canada's best interest.

“If I thought this project was unsafe for the B.C. coast, I would reject it,” he said.

The $6.8-billion project would triple the capacity of the Trans Mountain pipeline, from 300,000 to 890,000 barrels a day, and would add 980 kilometres of new pipe along the route from near Edmonton to Burnaby, B.C.

Mike Palecek, national president of the Canadian Union of Postal Workers, said his union stands in solidarity with those that oppose the pipeline.

“You can be serious about climate change, or you can expand the tar sands – but you can’t do both,” said Mike Palecek, national president of the Canadian Union of Postal Workers.

“I promise you sisters and brothers, we will be with you here in this struggle when things get real – and we know they’re going to.”

Vancouver Mayor Gregor Robertson said he was “profoundly disappointed,” calling the decision a “big step backwards” for Canada's environment and economy.

“I – along with the tens of thousands of residents, local First Nations, and other Metro Vancouver cities who told the federal government a resounding ‘no’ to this project – will keep speaking out against this pipeline expansion that doesn’t make sense for our economic or environmental future.”

Premier Christy Clark has insisted her government would not allow new pipeline construction unless five conditions were met, including a “world-leading” marine spill response regime. Earlier this month, Trudeau announced a $1.5-billion ocean-protection plan.

Clark was unavailable for comment Tuesday, but her Environment Minister Mary Polak said the province will continue to work to ensure each of its conditions are met.

With files from The Canadian Press