GREELEY, Colo. – JBS USA is working to lift South Korea’s ban against its beef products. South Korea halted imports of beef from JBS USA's Greeley, Colo., plant after finding a banned growth enhancer in the meat.

South Korea's food ministry halted imports from Swift Beef Co., a unit of JBS USA, and asked the United States to launch an investigation into the matter. Many Asian countries have banned feed additives such as zilpaterol. The feed additive came under scrutiny in the US after Springdale, Ark.-based Tyson Foods Inc. announced the company would no longer purchase cattle fed Zilmax, a brand of zilpaterol manufactured by Merck Animal Health. The company cited concerns the supplement may be causing lameness in beef cattle.

“We are working with our partners at the US Department of Agriculture and the South Korean government to resolve the issue concerning one of our US facilities,” JBS USA said in a statement. “Importantly, this is not a food-safety issue. In addition, the manufacturer of the feed additive in question has voluntarily suspended sales of the product in the US.”

Merck Animal Health stopped sales of the product in August and announced it would conduct a scientific audit to monitor the process of feeding Zilmax to cattle.