Canada has filed a comprehensive complaint with the World Trade Organization accusing the United States of breaking international trade rules. <br/><br/>The complaint challenges the ways that the US investigates products for subsidies and below-cost sales. However, the US called the claims unfounded. <br/><br/>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.<br/><br/>Thirty-two-page complaint by Canada cites US investigations of products from countries around the world, with decisions that date back to 1996.<br/><br/>