Ontario Premier Doug Ford kept up his criticism of a federal carbon tax Monday calling the plan "nothing more than a complete scam."

Ford made his latest attack on the planned tax alongside Saskatchewan Premier Scott Moe, who echoed Ford's remarks, calling a federal carbon tax a "sham" and a "vote-buying scheme." Both provinces are involved in a court challenge against the imposition of the tax.

Last week, Prime Minister Justin Trudeau went to Etobicoke — the riding Ford represents — to announce a federal carbon tax is coming to Ontario, which scrapped its cap-and-trade system earlier this year.

Ford's government hasn't announced what it will do to fight climate change, however, the premier said an announcement is coming soon about how it plans to tackle pollution. Queen's Park will come down on emitters, he said, like nothing they've seen before.

There was swift condemnation of Ford's statement.

Keith Stewart, a senior energy strategist with Greenpeace Canada, demanded Ford spell out exactly how his government will protect people from the dangers of climate change — including floods, heatwaves and powerful storms.

"If the two premiers dislike the federal carbon price, then all they have to do is meet or beat it with their own climate policy," Stewart said in an email to CBC Toronto.

Stewart added today's words amount to nothing more than an "evidence-free attack on climate action."

Ontario families to get $300 tax credit as part of federal plan

Trudeau has vowed every nickel raised from the federal tax will go back to Ontario.

Ottawa will levy a tax of $20 on every tonne of greenhouse gas emissions starting in 2019, rising by $10 each year to $50 a tonne by 2022.

Ontarians will likely pay more at the gas station as a result, but the federal government said most families will receive a tax break of about $300 per year.

Meanwhile, Ford said that amounts to "trying to buy Canadians with their own money," and warned the tax will drive up the price of virtually everything while also killing thousands of jobs.

"It's a terrible tax," he said.

Leaders sketch out trade deal

Ford added that he and Moe have signed a memorandum of understanding to lower trade barriers between Ontario and Saskatchewan.

Ford says that Canada has focused on free trade with the United States at the expense of internal trade.

The premiers say tackling interprovincial trade barriers is key to ensure Canada stays economically competitive.

"I hear from business leaders that this is one of the primary obstacles to attracting new investment and jobs to our country. We can't afford not to act," Ford said.

"I look forward to working with other provinces to bring these trade barriers down."