Chinese branches of Wal-Mart have been forced to recall batches of donkey meat after they were found to contain fox.
Local news reports say a man surnamed Wang bought 1,600 boxes of what he thought was donkey meat, but found it smelled strange.
He sent the product to a testing institute, which confirmed it was fox meat.
The supermarket initially said it suspected Wang of trying to extort money.
Donkey meat is a popular snack, but fox meat, a by-product of the fur trade, is far cheaper (it sells for about 70p a kilo).
It gives off an unpleasant fishy smell, and can be dangerous to humans because of parasites.
Wal-Mart operates more than 400 stores in China. It's competing with a number of market leaders including Tesco.
We are deeply sorry for this whole affair. It is a deep lesson that we need to continue to increase investment in supplier management.