Canada has filed a comprehensive complaint with the World Trade Organization accusing the United States of breaking international trade rules.
The complaint challenges the ways that the US investigates products for subsidies and below-cost sales. However, the US called the claims unfounded.
The action comes amid disputes between the two countries over areas such as dairy, aircraft sales and lumber as well as efforts to renegotiate the North American Free Trade Agreement.
Thirty-two-page complaint by Canada cites US investigations of products from countries around the world, with decisions that date back to 1996.