BEIJING: China's latest tainted product crisis widened Friday after tests found the chemical melamine in liquid milk produced by three of the country's leading dairy companies, the country's quality monitor said. The crisis roiling the nation's dairy industry was thought to have been initially confined to tainted milk powder and was blamed for four infant deaths, and illnesses in more than 6,200 others. But about 10 percent of liquid milk samples taken from the Mengniu Dairy Group and Yili Industrial Group - China's two largest dairy producers - contained melamine, according to the General Administration of Quality Supervision, Inspection and Quarantine. Milk from the Shanghai-based Bright Dairy also showed contamination. Melamine is a toxic industrial chemical that can cause kidney stones and lead to kidney failure. The agency would "severely punish those who are responsible," according to a notice posted on the agency's Web site. It said all the batches that tested positive were being recalled. Reactions were immediate, with Hong Kong's two biggest grocery chains, PARKnSHOP and Wellcome, pulling all liquid milk by Mengniu from the shelves. A day earlier, Hong Kong had recalled milk, yogurt, ice cream and other products made by the Yili Industrial Group. Starbucks said its 300 caf