Wal-Mart Stores Inc's British supermarket arm, Asda, said on Thursday it had discovered horse DNA in its beef bolognese sauce and was withdrawing that product and three others from its stores.

"We have a preliminary test result that suggests the presence of horse DNA in our 500g Beef Bolognese sauce. As you'd expect, we have withdrawn this product from our shelves," Asda spokeswoman Jo Newbould said. Asda has about 550 shops across the UK.