Official media say three children have died from nitrite poisoning after drinking milk from two dairies in northwestern China. Thirty-five others, mostly children, were sickened and are being treated.
The website of Pingliang News, a city government newspaper in Gansu province, said Friday one of the patients is in critical condition.
It said the dairies have been sealed off while their managers are investigated.
A staffer surnamed Huang at the city's Communist Party news office says authorities have asked food and health experts to determine the source of the nitrite.
In 2008, six children died and hundreds of thousands were sickened after drinking milk containing melamine, which raises nitrogen levels, making milk appear richer in protein.