Chinese and Hong Kong authorities have recalled tainted products
Nearly 53,000 children in China are now known to have been made ill by milk powder contaminated with the industrial chemical melamine, officials say.
About 13,000 of the victims remain in hospital, the health ministry added. Four children have died.
Chinese Prime Minister Wen Jiabao has visited sick children in hospitals and apologised for the food scandal.
Most victims are under two years old, and at least 104 of those in hospital are in a serious condition.
The health ministry announced the new figures Monday. It said the sick children had consumed milk powder from the Sanlu Group, the company where the contamination was first revealed two weeks ago.
Local media reports suggested the new number was the result of health officials' checks of hospital records from May this year to trace the origins of the contamination.
Children are checked in hospital
At least 22 other companies have since become involved in the scandal, and milk products made by the Yili, Mengniu and other groups have been recalled from supermarket shelves.
In Hong Kong, the two main supermarket chains, Wellcome and Park'n'Shop, are now recalling products made by Nestle, Dutch Lady and Mr Brown.
A local newspaper, the Chinese language Apple Daily, had conducted an unofficial test on Nestle pure milk and found traces of melamine. The result was later confirmed by Hong Kong government tests.
"Based on the low level detected, normal consumption will not pose major health effects. However, it is not advisable for small children to consumer the milk product," a spokesman for the government's Centre for Food Safety said.
Nestle said in a statement late on Sunday that it is "confident" that none of its Chinese-made products are made with milk contaminated with melamine. It said it "has the same stringent quality control system in place in its factories in China as in any other part of the world."
A three-year old girl in Hong Kong has been diagnosed with a kidney stone after drinking two glasses of Yili high calcium low-fat milk product for more than a year. Her symptoms were described as "mild". Tests are continuing on other infants in the territory.
In Taiwan, shops shelves carrying the Mr Brown brand of "three-in-one" coffee, in which coffee is mixed with sugar and milk, have been cleared.
In Singapore, the Chinese-made White Rabbit milk sweet has been found to carry traces of melamine and is being recalled, officials there said. Recalls of Chinese-made dairy products are now under way in Japan, Malaysia, and Brunei as well.
Mr Wen said he felt "extremely guilty" about the health scandal.
"I sincerely apologise to all of you," he said, after visiting sick children in hospital.
"What we are doing now is to ensure that nothing like this will ever happen again, and we are not only talking about milk. We will never let the same situation repeat with any kind of product.
"We can understand why parents have lost confidence (in hospitals). After the incident, there was a grave disturbance in my heart.
"Please trust us. We will empty the shelves of any milk product found to have a problem and destroy it so it cannot show up anywhere else."
Mr Wen also threatened harsh punishments for those found responsible for the contamination.
"Public confidence can only be rebuilt on merciless punishment," he said. "None of those companies lacking professional ethics or social morals will be let off."
Melamine is used in making plastics and is high in nitrogen, which makes products appear to have a higher protein count. Health experts say that ingesting small amounts does no harm, but sustained use can cause kidney stones and renal failure, especially among the young.
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