BEIJING (AP) -- A senior Chinese official has pledged to crack down on a nationwide milk-gathering system that he conceded was "out of control" and has led to abuses that put contaminated dairy products on store shelves across Asia.
The government has been scrambling for days to show it is tackling the problem after tainted baby formula sickened nearly 53,000 Chinese infants and killed four. Recent days have seen a number of arrests and forced resignations of officials over the widening scandal.
The World Health Organization on Tuesday warned of possible smuggling of the infant formula across borders.
Agriculture Minister Sun Zhengcai told a meeting with the health and public security ministries that the industrial chemical melamine was likely added at stations that collect milk from small individual dairy farmers.
"Since milk stations began only in recent years, the country now has no specific method of supervising them, or clear-cut supervision department. The purchasing process of raw milk is basically out of control," Sun said, according to a summary of his comments posted Tuesday on his ministry's Web site.
"We must crack down on them with the greatest determination and the toughest measures," Sun said in the meeting held late Monday.
Melamine, used to make plastics and fertilizer, has been found in infant formula and other milk products from 22 Chinese dairy companies. Suppliers trying to cut costs are believed to have added it to watered-down milk because its high nitrogen content masks the resulting protein deficiency.
The company at the center of the scandal, Sanlu Group Co., had no comment Tuesday about allegations on state television that the company had first received complaints about its infant formula more than a year ago.
A man who answered the telephone in the company president's office referred all questions to the media department. There, a female temporary worker promised to respond after informing her superiors. She refused to give her name.
China Central Television reported Monday night that an investigation by the State Council, China's Cabinet, found that Sanlu had been receiving complaints about its infant formula as early as December 2007. The dairy company discovered melamine in its milk powder in June but did not report it to city officials until Aug. 2, it said.
"During these eight months, the company did not inform the government and did not take proper measures, therefore making the situation worse," CCTV said.
The Shijiazhuang city government then failed to report the case to the Hebei provincial government until Sept. 9, CCTV said. Sanlu products were recalled from stores two days later and Shijiazhuang's top Communist Party official fired.
Anthony Hazzard, the Western Pacific director of the World Health Organization, said Tuesday that 82 percent of the children made sick by the formula were 2 years old or younger.
Hazzard said countries had been advised to focus particularly on smuggled formula by the International Food Safety Authorities (INFOSAN), a network of 167 countries organized by the WHO and the Food and Agriculture Organization.
He said authorities do not know at this stage what countries may have received the contaminated products.
"I think the greatest fear is if there has been illegal movement of the heavily contaminated products rather than the legal movement of products that may have very low levels of melamine," said Hazzard, speaking in Manila where the WHO's regional headquarters is located.
The scandal has also claimed the head of Li Changjiang, who stepped down Monday as boss of the General Administration of Quality Supervision, Inspection and Quarantine. Li had run the safety watchdog since 2001 and his resignation comes a year after he and the government promised to overhaul the system in response to a series of product safety scares.
New regulations and procedures were introduced in an attempt to restore consumer confidence and preserve export markets after a string of recalls involving tainted toothpaste, faulty tires, contaminated seafood and in March 2007, pet food containing melamine that was blamed for the deaths of dogs and cats in the United States.
According to the Health Ministry, of the 53,000 sickened children, 12,892 remain hospitalized, with 104 of them in serious condition. Another 39,965 children were treated and released.
Baby formula and other milk products have been pulled from stores around the country and Chinese dairy products have been recalled or banned in Japan, Singapore, Brunei, Malaysia and Hong Kong.
One of China's biggest milk producers, China Mengniu Dairy Co., saw its stock price plummet slightly more than 60 percent in Hong Kong trading Tuesday after its products were found tainted with the industrial chemical melamine.
Mengniu, China's No. 1 dairy producer in total volume, said only a small portion of its products were contaminated and blamed the contamination on "the illegal acts of some irresponsible milk collection centers and raw milk dealers."
"The board wishes to sincerely apologize for the incident and any inconvenience caused to the public," the company said in a statement to the Hong Kong stock exchange.