Prime Minister Stephen Harper's comments regarding the Liberal plan to cut carbon emissions were vulgar, Liberal Leader Stéphane Dion said Friday.

Dion was in Charlottetown to promote his "green shift" proposal, which would increase taxes on fossil fuels but lower taxes in other areas to make the plan revenue-neutral for the federal government.

When the plan was announced last month, Harper said the plan would "screw everybody."

"I think the prime minister must not be proud of himself, and especially when he used vulgar language. What a bad example to our youth," Dion told CBC News on Friday.

Harper also called the plan "insane." Dion described such attacks from the Conservatives as insulting to the intelligence of Canadians.

"If you had a lot of economists around the world saying the same thing, maybe the prime minister would have a point. But to the contrary, economists around the world are saying it's the best way to do carbon pricing, and have a strong economy," he said.

About 200 people turned out for a town hall on the "green shift" plan at the Arts Guild in Charlottetown on Friday afternoon.