The U.S. Department of Commerce found a higher level of dumping from some South Korean exporters of corrosion-resistant steel, raising the level of potential tariffs to as much as 48 percent from a preliminary rate of as much as 3.5 percent. Chinese producers of the metal may now face anti-dumping duties of 210 percent, compared with a preliminary finding of 256 percent in December. The commerce department’s announcement marks a final decision in the first of a series of trade cases in which domestic steel producers have accused producers in China and four other countries of selling the metal unfairly. It clears the way for the first duties to be assigned on steel products since the U.S. industry began filing cases a year ago. Companies including U.S. Steel Corp. and Nucor Corp. allege that steel mills in China, South Korea, India, Italy and Taiwan had dumped the metal in the U.S. The International Trade Commission is scheduled to make its decision next month on whether domestic steelmakers were injured by unfair trade, after which the government would order duties on the products. The rulings are part of a package of cases involving five different steel products, from basic steel coils to plates used by machinery manufacturers and products that have been treated for strength and flexibility and coated to prevent rust. The ruling harms the rights of Chinese companies, and China will take measures to ensure their fair treatment, the country’s ministry of commerce said in a statement. The anti-dumping rates imposed on Chinese imports are much higher than those from other regions, which is a discriminatory practice, it said.