Chinese state media is reporting that the Chinese firm whose baby formula is blamed for killing one infant and sickening dozens has accused dairy suppliers of adding a chemical to their milk to up protein content.
Chinese authorities announced a nationwide probe Friday into the Sanlu Group's milk powder as babies fell seriously ill with kidney stones across the country, in the latest scandal to rock China's food industry.
The state-run China News Service said an internal Sanlu investigation has found that a batch of baby powder produced prior to August 6 was found to be contaminated with melamine.
Melamine is a chemical used in plastics that was at the centre of a US recall of China-produced pet food last year.
"This was caused by dairy farmers illegally adding melamine to the milk to raise the protein content," the China News Service quoted the Sanlu report as saying.
The report gave no other information.
Xinhua news agency said police in Shijiazhuang had arrested 78 "suspects" in the case, but gave no further information.
China's health ministry on Friday ordered all its departments nationwide to immediately report every baby with kidney stones and difficulty urinating, symptoms of drinking the tainted milk formula.
One baby has died and many others have been hospitalised across the country with kidney stones after drinking milk made from Sanlu powder.
"A joint inter-ministerial team has been set up to investigate responsibility and strictly deal with those responsible," the ministry said of the team composed of police, health, commercial and drug agencies.
Pet food products in the United States were recalled after they were found to contain Chinese-produced ingredients contaminated with melamine.
The recall was prompted after numerous reports of sickened pets.