A third child in China has died in connection with tainted baby milk formula that has now sickened more than 6,000 others, China's health minister said Wednesday.

At least 6,244 infants have fallen ill after being fed the faulty formula, Chen Zhu told a news conference — up from 1,200 known illnesses the day before. He said 158 are suffering from acute kidney failure because of the contaminated milk powder.

A third child in eastern Zhejiang province has also died. Two earlier deaths were reported in Gansu province.

Two Chinese brothers have been arrested on accusations they deliberately added a toxic chemical to milk that was then supplied to the largest baby formula producer in China.

Chinese authorities said Tuesday inspectors have now found the chemical melamine in batches of milk powder produced by 22 companies out of the 109 tested.

Melamine reportedly boosts the appearance of protein in the baby formula, and is the same chemical used in fire retardants and other industrial products that was also found in pet food exported by China, which last year killed hundreds of cats and dogs in Canada and the United States.

Meanwhile, Chinese state media reported Tuesday that some of the milk products from one company had been exported to neighbouring Asian countries. It did not indicate which ones.

With files from the Associated Press