Nineteen affected Chinese families are making the allegation, state media reported.
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.
Again the inspection authorities have given the Wyeth's products a clean chit and said they were free of melamine, China Daily said, but went on to report at length the complaint of Li Xuefeng.
"At least 19 families with similar experiences have contacted me," Li said.
"But because we have no official reports showing that Wyeth products are unsafe, the only thing we can do is to gather as many cases as possible."
Wyeth said in a statement that its products were safe, according to the newspaper.
It said it had sent samples of 919 batches of milk products imported before September, and all milk powder products made in China, to government designated testing centers, but none were found to contain melamine.
All products imported after September were tested before entering China to ensure they were safe, and all products made domestically were tested by local quality control authorities before entering the market, the statement said.
"We have received complaints about kidney stones from consumers and care about their health," said Xi Qing, public relations director of Wyeth China.
"But so far there's no evidence to prove the kidney ailments are caused by our products. We're willing to cooperate and help find the real cause," he said.
The AQSIQ said on Sunday it had tested 2,935 batches of baby formula since September and all of them were qualified. The report did not mention particular brands.
To find out the cause of the kidney ailments, the Ministry of Health said last week that it was conducting a nationwide epidemiological study into the Dumex case, as it did with Wyeth, the paper said. No conclusion had been made as of yesterday.
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.
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, Xinhua news agency said.
Clearly China is not going to let go of any opportunity to damn the West.