Four children have died and upwards of 6,000 are sick from products contaminated with melamine, a chemical used plastics, the BBC reported Saturday.

The contamination, thought to be restricted to powdered milk, was confirmed Friday in 10 percent of liquid milk tested from three of China's dairies, reported Xinhua, China's state-run news agency.

China's Cabinet has set up 24 telephone hotlines to provide medical advice to parents and ordered free intensive medical treatment for stricken children, Xinhua said.

More than 150 of the sickened children are said to have acute kidney failure and many more have developed kidney stones from drinking the contaminated milk, the BBC reported.

Suppliers are suspected of adding melamine to watered-down milk products to boost the nitrogen content, allowing the milk to pass quality-control standards, the BBC reported.