BEIJING (AP) -- Fifteen more Chinese dairy companies were identified Wednesday as producing milk products contaminated with an industrial chemical, further broadening a scandal affecting products ranging from baby formula to chocolate, authorities said.
The contamination has been blamed for the deaths of four children and kidney ailments among 54,000 others. More than 13,000 children have been hospitalized and 27 people arrested in connection with the tainting.
An additional 31 batches of Chinese milk powder were found tainted with the industrial chemical melamine, according to data seen on the food safety administration's Web site Wednesday. Out of the 20 companies on the list, 15 have not been named in previous tests.
The new batches being tested were mostly milk powder products for adults. A previous round of tests found melamine in 69 infant milk powder batches.
The new figure brings to at least 100 the number of tested batches of milk powder found to contain melamine. Dozens of brands sold by more than a score of dairy firms, including some of China's biggest names, have been among those tested.
Tests have also found melamine in 24 batches of liquid milk produced by three of the country's best known dairy firms.
It was a national holiday in China and product safety officials could not be reached for comment.
The Web site quoted the State Administration of Quality Supervision, Inspection and Quarantine as saying it had tested 265 batches produced by 154 different companies prior to Sept. 14. China has a total of 290 companies making powdered milk, the administration said.
In the most recent tests, nine of the batches containing melamine were produced by the company at the center of the scandal, Sanlu, a 43 percent stake of which is owned by New Zealand dairy cooperative Fonterra. No date for the testing was given.
Melamine, which is high in nitrogen, is used to make plastics and fertilizers and experts say some amount of the chemical may be transferred from the environment during food processing. But in China's case, suppliers trying to boost output are believed to have diluted their milk, adding melamine because its nitrogen content can fool tests aimed at verifying protein content.
Melamine can cause kidney stones, leading to kidney failure. Infants are particularly vulnerable.
The scandal was worsened by an apparent cover-up by companies involved and the ignoring by safety officials of tips and warnings from parents and doctors. Top Sanlu executives and government officials in the northern city of Shijiazhuang, where the company is based, have been forced to resign.
Also on Wednesday, Hong Kong's food safety agency said its tests have found melamine in a Japanese brand's Chinese-made cheesecake. The agency said a sample of Lotte Cream Cheese Cake manufactured by Japan's Lotte China Foods Co. Ltd in mainland China was found to contain melamine.
Hong Kong and Macau authorities earlier detected excessive melamine in Lotte's popular Koala's March chocolate and strawberry cream cookies.
In Thailand, where food inspectors said they are testing nearly 100 imports from China for possible contamination, the country's public health minister, Chalerm Yoobamrung, said Wednesday that they should monitor the situation closely but should not "hype up (the issue) too much."
"I did not mean that I am afraid of China, but we have to be concerned about our trade ties because Thailand does a lot of business with China," he said.