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

Wyeth is also involved in the notorious milk powder scandal.

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.

However, the AQSIQ said in a report published the same month that Wyeth's products were free of melamine.

"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 sent a statement to China Daily yesterday saying its products are safe.

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," Xi Qing, public relations director of Wyeth China, told China Daily.

"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 has 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. No conclusion had been made as of yesterday.