The 19-month baby has been fed on Wyeth milk powder since birth. He was diagnosed with a stone in his kidney last year.

Health experts have said it is too early to point fingers at milk powder producers.

Chen Junshi, a senior researcher with the National Institute for Nutrition and Food Safety, said although kidney stones rarely develop in young children, they can be triggered by various reasons, such as feeding habits or families' living environments.

"We need scientific research and evidence," he said.

Tang Zhiqing, a dairy industry analyst who has worked for both domestic dairy firms Bright Dairy and Mengniu, said complaints against Dumex and Wyeth were possibly started by rival firms seeking to gain a competitive advantage.

The accusations against Wyeth have already dented its reputation. An online poll at Sina.com found that 61 percent of about 10,000 respondents said the accusation will affect their future purchasing decisions.

(China Daily February 24, 2009)