WASHINGTON (AFP) - The United States launched a probe Wednesday to consider slapping almost 100 percent tariffs on imported steel pipes from China in a move that could widen a trade spat between the two key powers. Washington has decided to initiate antidumping and countervailing duty investigations on imports of Chinese seamless pipes used to convey water, steam, chemicals, oil products and natural gas, the Commerce Dept said. The pipes were allegedly backed by unfair subsidies. Dumping occurs when a foreign company sells a product in the United States at less than normal value. Subsidies are financial assistance from foreign governments that benefit the production, manufacture, or exportation of goods. The Commerce Departments action came less than a month after US President Barack Obama imposed punitive duties on Chinese-made tires, igniting the first trade spat of his presidency. An angry Beijing lodged a complaint at the World Trade Organization and retaliated by launching a probe into possible unfair trade practices involving imports of US car products and chicken meat. Beijing charged that Washingtons move violated WTO rules but Obama has denied that it amounted to protectionism. Just last week, the New York Times reported that Washington had imposed tariffs on imports of solar panels, which had become too sophisticated to qualify for duty-free import. China is reputedly the worlds biggest solar-panel manufacturer. The Commerce Dept said the move to consider imposing tariffs on steel pipe imports stemmed from a petition from companies such as the US Steel Corp as well as the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers Int'l Union. A preliminary injury determination on the steel pipe probe was expected to be made by the quasi-judicial US International Trade Commission on Nov 2, the department said. Duties if imposed could reach a whopping 100pc. According to a fact sheet provided by the department, the alleged dumping margin is 98.37pc. If the ITC determines that there is a reasonable indication that imports are materially injuring, or threatening material injury to, the domestic industry, the investigations will continue, and Commerce will be scheduled to make its preliminary CVD (countervail-ing duty) determination in Dec 2009 and its preliminary AD (antidumping) determinations in February 2010, it said. From 2006 to 2008, imports of seamless pipes from China increased more than 131 percent by volume and were valued at an estimated 382 million dollars last year, the department said. Also last month, the United States made a preliminary decision to impose tariffs as much as 31 percent on another kind of steel pipe imported from China and used mostly in oil and gas wells. It drew a quick and angry response from Beijing, which called it a protectionist step. Obama has vowed to fight tenaciously for Americas trade rights but dismissed fears of a trade war with China, pointing out that Washington was merely enforcing trade agreements, part and parcel of maintaining an open and free trading system.