Wal-Mart Stores Inc. has recalled donkey meat sold at some outlets in China after DNA tests revealed the meat is contaminated with other animal products, Reuters reported.

The Shandong Food and Drug Administration announced earlier this week that the "Five Spice" donkey meat, a popular snack in some areas of China, contained fox meat, Reuters reported.

"This is another hit on Wal-Mart's brand, meaning wealthy shoppers will start to lose the trust they had before," Shaun Rein, Shanghai-based managing director of China Market Research (CMR) Group, told Reuters.

The retailer is helping local food and industry agencies in eastern Shandong province investigate its Chinese supplier Dezhou Fujude Food Company Ltd. In a statement released yesterday, Wal-Mart officials said they "immediately withdrew and sealed all products from [Dezhou Fujude Food Company]" after learning the supplier had produced and provided its retail stores and other distributors donkey meat containing fox DNA.

China authorities have put Dezhou Fujude officials in "criminal detention" and Wal-Mart is considering legal action, Bloomberg News reported.

"Walmart will spare no effort in fulfilling its obligations as a retailer and in working with government authorities in their investigation," Greg Foran, Wal-Mart's China president, said in the statement yesterday. "Walmart commits to further enhance sample testing in the future."

According to Reuters, Wal-Mart said it will reimburse customers who bought the tainted product. The retailer said it also will add DNA tests to its sample tests of meat products.

The additional testing will go beyond what is legally required in China to "ensure high quality and safety of the products sold in Walmart stores," Wal-Mart said in a statement.

Foran said the recent incident "has provided a deep lesson that we need to continue to increase investment in supplier management."

According to Reuters, the U.S. retailer has had a troubled past in China.

In 2011, China fined Wal-Mart, along with Carrefour, a combined $1.57 million for manipulating product prices. That year, Wal-Mart was also fined for selling duck meat past its expiry date.