China's quality watchdog says the tainted product crisis has extended to liquid milk.

The General Administration of Quality Supervision, Inspection and Quarantine says milk sold in liquid form by three leading Chinese dairies is contaminated with melamine

A report posted Friday on the agency's Web site says test results show nearly 10 percent of samples taken from Mengniu Dairy Group Co. and Yili Industrial Group Co. — China's two largest dairy companies — contained up to 8.4 milligrams of melamine per kilogram.

Milk from Shanghai-based Bright Dairy also shows melamine contamination.

The crisis began after the industrial chemical melamine was found in milk powder, which has been linked to four infant deaths and illnesses in 6,200 others.