FILE PHOTO: Steam rises from a plant in an industrial zone in Hamilton

By Moira Warburton

TORONTO (Reuters) - The province of Ontario has taken its fight against the Canadian federal government's carbon tax to the country's top court, after losing an initial challenge in a lower court.

The Ontario government said on Wednesday it filed an appeal of the federal carbon tax in Canada's Supreme Court, arguing that the carbon tax, enacted by Prime Minister Justin Trudeau's Liberal government in April, was unconstitutional.

Trudeau instituted a federal carbon tax in Ontario - as well as Saskatchewan, Manitoba and New Brunswick - after they failed to implement a provincial carbon tax.

"We remain committed to using every tool at our disposal to fight against the job-killing carbon tax," Jeff Yurek, Ontario minister of environment, said in a statement.

In June the Ontario Court of Appeal rejected Ontario's argument that the carbon tax was unconstitutional.

Ontario is not alone in suing the federal government over the carbon tax, which is expected to be a key - and polarizing - issue in Canada's October federal election.

Saskatchewan, Alberta and Manitoba have also each filed their own lawsuits against the carbon tax and a favorable ruling from the Supreme Court for the Ontario government could allow the provinces to remove the tax.

Trudeau's Liberal Party supporters rank it among their top concerns, while Andrew Scheer's Conservative backers put it near the bottom of their list of priorities.

In June, Scheer unveiled his long-awaited climate and environment plan that would eliminate the current federal carbon pricing if voted to power.

Federal Finance Minister Bill Morneau slammed Ontario's court challenge on Wednesday.

Ontario Premier Doug Ford "has no plan for the environment beyond stickers on gas pumps and now a costly and unnecessary Supreme Court challenge," Morneau said in a statement.

"This is not the course Ontarians want their government to take but we will defend our plan because it is the right thing to do now and for our future."





(Reporting by Moira Warburton; Editing by Denny Thomas and Lisa Shumaker)