A third U.S. company recalled pet foods made with an imported Chinese ingredient only recently found to have been contaminated by an industrial chemical.

The pet food ingredient, rice protein concentrate, is the second found in the U.S. to be contaminated by melamine. Previously, testing revealed that wheat gluten also had been contaminated.

Click here for a list of some contaminated pet food brands.

Royal Canin USA said Friday that it was recalling some of its dry dog and cat foods made with tainted rice protein concentrate.

Also this week, the French company's South African unit recalled a range of dog and cat dry pet foods after they were found to contain a third ingredient, corn gluten, also contaminated with melamine. Those products were sold in South Africa and Namibia.

Customers with questions about Royal Canin's recall can visit its Web site: http://www.royalcanin.us .

Wilbur-Ellis Co., a U.S. importer of the tainted rice protein, has recalled all the ingredient it had distributed to five U.S. pet food manufacturers. The San Francisco company in turn urged its customers to recall any products that may be on store shelves.

Earlier this week, two other pet food companies, Natural Balance Blue Buffalo, recalled cat and dog foods made with the contaminated rice protein concentrate.