Chinese state media say three children have died in northwest China from suspected poisoning after drinking tainted milk. Thirty-five other people, mostly children, are being treated at hospitals in Gansu province.
Authorities have launched an investigation into the latest scandal to hit China's dairies.
Beijing officials, quoted by the official Xinhua news agency, said Friday an initial investigation into the tainted milk deaths indicates the victims were poisoned by nitrate added to their milk.
Nitrate is a chemical usually used for curing meat. Several producers have been caught, in the past, adding often lethal chemicals as protein substitutes to fool quality inspectors.
The latest incident comes a week after the government closed half of the country's 1,200 dairy producers as part of a crackdown to clean up the industry.
Matthew Crabbe is a China consumer expert whose Shanghai-based consultancy has published reports on the country's dairy industry. He says the dairy sector may have to undergo more cuts of small producers before consumers regain confidence in dairy products.
"In order to regain consumer confidence there has to be more security in the whole system and the way dairy products are produced," Crabbe says. "The only way to do that is to weed out bad elements, and consolidate so you have fewer companies producing and more competition in the market. And those companies remaining need complete control over their supply so they know 100 percent the raw material, right through to the finest finished product, is completely secure," he says.
The worst case of tainted milk occurred in 2008. At least six infants died and nearly 300,000 others fell ill after drinking baby formula milk powder laced with the industrial chemical malamine to beat protein quality tests.
The scandal led to a worldwide recall of Chinese dairy products.