But Mr Trudeau said there was still work to be done and called for US tariffs on steel and aluminium to be scrapped. The three leaders signed the The United States-Mexico-Canada Agreement at the start of the G20 summit on Friday. Mr Trudeau said: "There is much more work to do in lowering trade barriers, but reaching a new trade agreement with the USA and Mexico is a major step for the world economy."

The three-way trade agreement replaces the 24-year-old North American Free Trade Agreement.

Mr Trudeau added: “Free and fair trade leads to better jobs for middle-class people.

"The new agreement risks the risk of serious economic uncertainly that lingers throughout a trade negotiation process.

"Uncertainty that would only have got worse if we had not reached a new NAFTA."

Mr Trudeau added that "the benefits of free trade must be broadly and fairly shared", before criticising US tariffs on steel and aluminium.

He described General Motors' plant closures that had hit thousands of US and Canadian families as a “heavy blow”.

Mr Trudeau vowed: “Make no mistake we will stand up for our workers and fight for their families and communities."

Addressing Mr Trump, Mr Trudeau said: “And Donald, its all the more reason we need keep working to remove tariffs on steel and aluminium between our countries.”

He added: "The task isn’t done. There is more hard work to build resilient strong economies that support families everywhere in Canada".