WASHINGTON, June 3 (Reuters) - The U.S. International Trade Commission said on Tuesday that cheap imports of concrete steel rail tie wire from China and Mexico are hurting local manufacturers, a ruling that will lead to anti-dumping duties on the products.

In their final ruling on the prestressed wire, which is primarily used in commuter and high-speed rail lines, ITC commissioners voted unanimously to back the complaint by U.S. producers.

The duties on Chinese imports will be between 31.4 percent and 35.3 percent, in line with margins set earlier by the U.S. Commerce Department. Mexican imports will attract a 9.99 percent duty.

The complaint was lodged by Insteel Wire Products Co, a division of Insteel Industries, and Davis Wire Corp. In 2013, imports of the wire from China were valued at $31.1 million and from Mexico at $21.3 million. (Reporting by Krista Hughes )