Beijing - A top health official yesterday blamed China's biggest milk powder producer for keeping mum about its tainted infant formula for months. At least 432 babies have already developed kidney stones because of the delay.

Shijiazhuang-based Sanlu Group received consumer complaints as early as March this year, said Mr Gao Qiang, a senior Health Ministry official.

Internal investigations confirmed a batch of its milk formula made before Aug 6 this year was contaminated with melamine, a chemical used in plastics and cleaning products that could cause kidney stones and failure if ingested.

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