Mrs May will also meet the head of Bombardier before a key USA trade ruling on the dispute that, if it goes against the company, could cost 4,500 jobs at the company's factory in Belfast.
British Prime Minister Theresa May said on Monday she would press U.S. President Donald Trump this week about a trade challenge by Boeing Co that could endanger thousands of aerospace jobs in Northern Ireland.
Canadian Prime Minister Justin Trudeau said here on Monday that his country will not do business with USA aerospace giant Boeing because the company has sued a Canadian company.
These include the expansion of Vancouver-based social media company Hootsuite in London, the supply of Tesco's product range to 100 West Coast supermarkets by the end of this year, and a £34 million Turner and Townsend contract to oversee refurbishment of part of the Canadian Parliament.
"We will continue to stand up for jobs and stand up for the excellent airplane that is the Bombardier CSeries aircraft", Trudeau said.
Boeing opened a case against Bombardier at the Commerce Department's International Trade Commission in April accusing the company of dumping its C Series passenger jets into the USA market at "absurdly low prices".
The U.S. State Department last week cleared Boeing to sell the fighter jets to Canada, even as the potential political ramifications of Boeing's suit against Bombardier continued to unfold.More news: Danica Patrick out at Stewart-Haas Racing
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The row involves a 2016 order from U.S. airline Delta for up to 125 C-Series planes, whose wings are built in Belfast.
Speaking ahead of her visit, Mrs May said that Canada and the United Kingdom form a "powerful union" when they work together on priorities like free trade.
"Boeing is not suing Canada". A US trade court is due to give a preliminary ruling on Boeing's complaint on September 25. "But competition and sales must respect globally-accepted trade law", it added.
The Prime Minister was facing calls to sack Foreign Secretary Boris Johnson, who was branded a "backseat driver" by a Cabinet colleague after setting out his own vision for a hard Brexit just days before a major speech in which Mrs May is expected to offer compromise.
Trudeau said Boeing's actions are harmful to jobs in Canada, to economic growth here and "also harmful to the future of the aerospace industry in the whole world". The Democratic Unionist Party agreed to prop up the May government earlier this year in return for economic investment in Northern Ireland.
"But we won't do business with a company that's busy trying to sue us and trying to put our aerospace workers out of business".