May and Prime Minister Justin Trudeau are anxious about Boeing's move against Bombardier Inc, which is the single largest manufacturing employer in Northern Ireland and Canada's most important aerospace firm. The deal could potentially involve the purchase of 18 jets at a cost of more than $5 billion.
"I will raise the issue of Bombardier when I meet with him again later this week", said May.
Britain is Canada's largest trading partner in Europe and can take advantage of CETA as long as it remains a part of the European Union, but not after Brexit in 2019.
Trudeau made the comments today during an appearance with British Prime Minister Theresa May, who says Canada and the United Kingdom will work together to defend Bombardier, which has a factory in Northern Ireland.
Boeing has accused of Bombardier of selling its CSeries passenger jets to a USA airline at an unfairly low price with help from government subsidies, and says the case affects its long-term economic health.
The case was inspired by the 2016 purchase by Delta Air Lines to buy up to 125 C Series airliners from Bombardier. An initial ruling by the ITC is expected as early as September 25, according the aviation industry officials. Bombardier's aerospace division employs 28,500 people worldwide.
"But we won't do business with a company that's busy trying to sue us and put our aerospace workers out of business". A USA trade court is due to give a preliminary ruling on Boeing's complaint on September 25.
"Sinn Fein has influence on Capitol Hill - the United States politicians must be shown the impact an adverse decision by the Department of Commerce would have on the Northern Ireland economy, an economy which continues to struggle with the legacy of conflict, underinvestment and dislocation as well as the potential threats arising from Brexit". May's minority Conservative government depends on backing from the small Northern Irish Democratic Unionist Party (DUP) for their majority control of the British parliament.
Boeing did not immediately respond to a request for comment about the statements from Trudeau and May.