By Li Hongmei

Wal-Mart said yesterday in a statement that it withdrew all products from the supplier, Dezhou Fujude Food Company Ltd., after finding fox DNA in tested samples. Dezhou Fujude officials have been placed in criminal detention, Wal-Mart said.

Wal-Mart, the world's largest retailer, has faced other food safety and labeling problems in China, including a 2012 citation by regulators for selling sesame oil and squid with hazardous levels of chemicals.

Other Western companies in the Asian nation have also dealt with contamination concerns. Yum! Brand's Inc.'s KFC stores faced a customer backlash after a former supplier was investigated for selling chicken with too many antibiotics and an avian flu outbreak scared diners away.

"While this appears to be an isolated incident to select stores in China, our customers' trust is paramount for our business and we are deeply sorry for this incident," Wal-Mart said yesterday. Donkey meat is "a popular delicacy in China," the Bentonville, Arkansas-based retailer said.

Last year, Wal-Mart said it would invest 100 million yuan ($16.5 million) over three years to upgrade food safety in China by adding a mobile food-inspection program and increasing supplier training.

Wal-Mart said it has boosted random testing in the past year and helped found the Food Fraud Think Tank to deter contamination.