BEIJING (AP) -- Chinese authorities secretly investigated a dairy for nearly a year before announcing the company had been producing milk tainted with an industrial chemical, reflecting the country's unease with the transparency needed to restore public confidence in food safety.
The Shanghai dairy had been part of one of China's worst food safety crises, the 2008 tainted milk scandal in which six children died and more than 300,000 fell sick after drinking baby formula contaminated with an industrial chemical. Dairy and local officials were accused of keeping the scandal quiet until after the Beijing Olympics.
The government promised sweeping changes and more openness after the milk powder deaths became public, but a city official on Thursday said that authorities knew about the latest contamination in Shanghai Panda Dairy Co. products last February -- and then kept it quiet until a vague announcement on New Year's Eve.
"We paid a very high price back in 2008 for the milk powder scandal, but now it seems the authorities still haven't learned their lesson from it," said Wang Xixin, a Peking University law professor.
Food safety authorities have not said if anyone has been sickened by consuming tainted milk products produced by Shanghai Panda. Calls to the company rang unanswered Thursday and its Web site was shut down.
China enacted a food safety law early last year after the milk scandal, saying authorities should immediately tell the public when food products have been found unsafe for consumption.
Chinese authorities, however, often have been unwilling to promptly publicize negative news for fear of being punished.
Notable examples include the apparent cover-up in 2003 of the early spread of severe acute respiratory syndrome, or SARS, in China, and a major chemical spill on the Songhua River in 2005 that officials didn't announce for 10 days. Last fall, more than 50 local officials and journalists were accused of helping to cover up a coal mine disaster that killed 35 people shortly before the Olympics.
In this latest case, Shanghai food safety authorities said they found contamination in Shanghai Panda's products last February, immediately started investigating, seized all the tainted products and in April detained three executives.
But food safety authorities only told the public last week, when they shut the dairy.
They said Shanghai Panda was selling milk powder and condensed milk tainted with the industrial chemical melamine, which can cause kidney stones and kidney failure — the same chemical in the 2008 scandal.
Melamine, normally used in the manufacture of plastics and fertilizer, was added to watered-down milk to fool inspectors testing for protein and increase profits.
Shanghai Panda was one of the 22 dairies named by China's product safety authority in the 2008 scandal, and tests at the time showed its products had among the highest levels of melamine.
The company suspended operations amid the investigations but was allowed to resume production later after it pledged to improve safety standards.
It was not clear how much time passed between the company resuming production and officials finding the latest contamination last February.
The case was not allowed to be made public in April, when the executives were detained, because it was still under investigation, said Shen Weiping, a spokesman for the prosecutor's office in Shanghai's Fengxian district, where the dairy is located.
But Xu Zhiyong, a legal scholar who has assisted parents whose children were sickened in the 2008 milk scandal, said food inspection authorities should have told the public.
"I don't agree with saying that no detail can be revealed due to an investigation. You can of course say the case is being investigated," Xu said. "It would be more serious and would hurt people's confidence in our food safety if our government hides the truth."
If Shanghai Panda products do have quality problems and authorities knew about it in advance, the authorities must bear the legal responsibility for failing to do their duty, Wang of Peking University said.
"Consumer confidence in Chinese milk products is still recovering from the 2008 scandal, but this will deal it another big blow."
Associated Press researchers Xi Yue in Beijing and Ji Chen in Shanghai contributed to this report.