Chinese officials are investigating a brand of baby formula after more than a dozen babies who drank it developed kidney stones, state media has said.
Reports of the problem first emerged on Wednesday, when 14 babies in Gansu province were said to have become ill.
According to Xinhua news agency, similar cases have now appeared in northern, eastern and central China.
One baby has reportedly died, but officials have not yet drawn a clear link with the milk powder in this case.
The babies in Gansu had all been fed milk powder bearing the label of the Sanlu Group, but a spokesperson for Sanlu insisted that any substandard milk would have produced by counterfeiters.
"It is extremely rare for babies to get kidney stones, let alone so many getting them all at the same time," said Zhang Wei, chief urologist at the Gansu hospital where the 14 babies are being treated.
He told the China Daily newspaper that it was possible more babies in the area could have been taken ill, but high medical costs might have deterred parents from coming for treatment.
Xinhua reported on Thursday that other cases had emerged in the provinces of Jiangsu, Shandong, Ningxia, Shaanxi, Anhui and Hunan.
A fake milk powder scandal in 2004 killed at least 13 babies in the eastern province of Anhui.
Investigators found that the milk given to these babies had no nutritional value, and the resulting scandal triggered widespread investigations into food safety.