China has turned away two batches — roughly 546,000 tons — of U.S. dried distillers' grains due to its genetically modified contents, state media reported on Friday.
China's food-quality regulator rejected the two batches of corn byproduct because it contained MIR162, an insect-resistant strain made of maize developed by Syngenta, a Swiss company that makes seeds and pesticides.
MIR162 is not on China's agriculture ministry's short list of approved genetically modified organisms, known as GMOs.
The United States is the world's largest exporter of corn and China is the No. 3 importer, according to the Los Angeles Times.
Upon returning the shipments, Chinese authorities warned the U.S. to "improve its inspection procedures to ensure that they comply with Chinese quality standards."