SHANGHAI  One of China’s biggest dairy producers received consumer complaints about its baby milk formula as early as December 2007  much earlier than previously thought and 10 months before the producer ordered a nationwide recall because of concerns that the formula had been adulterated with a toxic industrial chemical, state media said Tuesday.

The disclosure, in a government report publicized by the official Xinhua News Agency, is the latest indication that the producer, Sanlu Group, had repeatedly tried to hide information about its contaminated dairy supplies from the public.

Powdered milk formula in China tainted by melamine, a chemical compound, has already sickened more than 53,000 infants and killed three children nationwide, according to the Health Ministry, leading to recalls of Chinese-made dairy products in China and other parts of Asia, devastating this nation’s huge dairy industry and casting a renewed pall over the quality of Chinese food production. Officials at the Sanlu Group, which is based in northern China’s Hebei Province, could not be reached for comment on Tuesday.

The government report did not include details about the nature or number of consumer complaints but put the timing of when they began at least six months earlier than first reported.