Nineteen families complained yesterday that their children had developed kidney stones after drinking the milk powder made by Wyeth.

This is the second foreign company - after Dumex, a unit of France's Danone - to face such accusations. More than 100 children reportedly fell ill after drinking Dumex milk food, although the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) said last week the company's baby food was free of melamine.

Li Xuefeng, a father from Chongqing and head of a local family group, said his 2-year-old son had been fed on baby milk formula of Wyeth since birth. In September, he was diagnosed with a stone in his left kidney.