Two major South Korean retailers pulled American beef from their grocery shelves on Wednesday, reacting swiftly to news that mad-cow disease was discovered in a U.S. cow and hoping to avoid customer protests. The South Korean government said it will continue to import U.S. beef but increase its inspections of the product at ports of entry. The country was the fourth-biggest importer of U.S. beef last year. In a statement, South Korea\'s Agriculture Ministry said it would also seek more details about the reported case of mad-cow disease in a California dairy cow, the first such incidence of the disease in U.S. livestock since 2006. Two of South Korea\'s largest grocery chains, Lotte Group\'s Lotte Mart chain and Tesco Corp.\'s TESO +1.90% HomePlus, announced they had removed U.S. beef from their stores. Mad-cow disease, which can cause a fatal illness in people who eat infected cattle products, is a particularly sensitive issue in South Korea\'s trade relationship with the U.S. South Koreans for three months in 2008 protested the government\'s decision to resume imports of U.S. beef that were blocked in 2003 after a case of mad-cow disease was reported in Washington state. The protests ended after South Korean officials restricted purchases to meat from cattle under 30 months old, which are less vulnerable to picking up the disease. U.S. beef consumption in South Korea rose rapidly after the ban was lifted and now accounts for about 40% of the beef that the country imports. However, South Korea today still purchases less beef in volume from the U.S. than it did before the 2003 restriction. Meanwhile, the political and emotional impact of the protests, which sometimes drew tens of thousands of people to a plaza in central Seoul, has lingered. In the weeks after the ban was lifted, some Korean farmers and others staged surprise protests inside grocery stores, ripping open packages of U.S. beef and preventing consumers from buying it. Opposition politicians at the time used the issue to portray President Lee Myung-bak, who was then new to the job, as too willing to do what the U.S. wanted. In response to the protest, Mr. Lee replaced several members of his cabinet and scrapped an ambitious agenda for economic reform. The 2008 protests also led South Korea to improve its animal health inspection. Starting that year, the government began to randomly test approximately 15,000 to 20,000 cattle annually for mad-cow disease. No cases have been reported through such tests.