By AUDRA ANG Associated Press Writer

BEIJING (AP) - China said Friday it had shut down a chemical plant implicated in the deaths of 94 people in Panama from medicine containing an antifreeze ingredient and also closed two companies whose products have been linked to the deaths of dozens of pets in North America.

China's quality control agency also said police were investigating two of the companies - Xuzhou Anying Biologic Technology Development Co. Ltd. and Binzhou Futian Biology Technology Co. Ltd. It did not elaborate.

The two companies, along with Taixing Glycerin Factory, are at the heart of the food and drug safety scares that in recent months have damaged China's reputation as a reliable exporter. While the government has announced the detention of an unspecified number of managers from Xuzhou Anying and Binzhou Futian, Friday's actions are the most severe and definitive taken against the companies.

The measures appear to be aimed at reassuring global customers that China takes seriously the concerns over chemicals and toxins that have been found in its products.

Following the pet food deaths, U.S. authorities have turned away or recalled toxic fish, juice containing unsafe color additives and popular toy trains decorated with lead paint. Chinese-made toothpaste containing DEG has also been rejected or recalled in Japan, Singapore and Australia.

The General Administration for Quality Supervision, Inspection and Quarantine said it had revoked the licenses of the three companies and shut down their offices and workshops.

Telephones at the three were not answered or were no longer in service.

The Taixing Glycerin Factory had been accused of selling what it called industrial ``TD glycerin'' a mix of 15 percent diethylene glycol and other substances.

Diethylene glycol, or DEG, is a thickening agent used in antifreeze and as a low-cost, but frequently deadly, substitute for glycerin, a sweetener commonly used in drugs.

``Its workshop and facilities have been closed down by the Jiangsu province and its business license revoked,'' the statement said.

Chinese quality officials have said ``TD glycerin'' is a misleading label because it could be mistaken for glycerin.

But they have also said the bulk of the blame lies with Panamanian merchants, who fraudulently mislabeled the ``TD glycerin'' as medical glycerine and for altering the use-by date of the already expired product.

It eventually ended up in Panamanian cough syrup and other medicines that killed at least 94 people.

The statement also detailed punishments against Xuzhou Anying and Binzhou Futian, the two companies linked to melamine-tainted wheat gluten blamed for the deaths of dozens of dogs and cats in North America.

Xuzhou Anying, also in Jiangsu province, ``unlawfully added melamine in some of its products which could not meet the protein content requirement set in the contracts,'' the administration said. ``This behavior of adulteration severely violated the feed quality and safety standards.''

Binzhou Futian, headquartered in neighboring Shandong province, ``added melamine in some of its products which could not meet the protein content requirement ... constituting severe adulteration,'' the statement said.

Melamine, used in plastics, fertilizers and flame retardants, has no nutritional value but is high in nitrogen, making products to which it is added appear to be higher in protein - a way to cut costs for the manufacturer.

China also has accused the companies of illegally mislabeling their exported products to avoid inspections. All have been banned from exporting.

U.S. Department of Health and Human Services and Chinese food safety authorities will meet in late July to discuss China's seafood exports.

Tensions were triggered last month after the U.S. Food and Drug Administration announced it would seize Chinese catfish, basa and dace, as well as shrimp and eel, after repeated testing turned up contamination with drugs that have not been approved in the United States for use in farmed seafood.

Li said an investigation has found that some fish farms ``did use banned substances in those exports'' and were not officially registered, allowing them to slip through without detection.

However, Li also said that the U.S. had an import system that relied on random tests and did not require quarantine certificates for customs clearance.

Li said the one of biggest problems in food safety is the regulatory nightmare of countless small and illegal food manufacturers that are springing up throughout the country.

``We will resolutely close down these small food manufactures ... who are engaged in producing substandard or fake or shoddy food and they will not be allowed to restart their business,'' Li said.

Also Friday, Chinese state media said at least seven more people have been fired or reprimanded over an allegedly fake television report about a street vendor selling buns stuffed with chemically treated cardboard.

Footage appeared to show a makeshift kitchen where people made buns stuffed with mixture of fatty pork and cardboard that had been softened to a pulp in caustic soda.