The General Administration of Quality Supervision, Inspection and Quarantine found that products from Mengniu Dairy Group, Yili Industrial Group and Shanghai-based Bright Dairy all contained the chemical, which is normally used in plastics and is banned from food stuffs.
Suppliers are suspected of diluting milk to cut costs, then adding melamine to make it appear higher in protein, the report said.
The scandal first came to light in baby milk formula that killed four infants and sickened more than 6,000 others.
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