The nationwide crackdown, which the government said began last December, also found that many small food makers were using industrial chemicals, banned dyes and other illegal ingredients in things like candy and seafood.
The announcement came as part of an overhaul of food safety regulations after a series of international food scares involving Chinese exports.
The country’s exports of contaminated ingredients for animal feed earlier this year led to one of the largest pet food recalls in American history.
Tainted animal feed ingredients also leached into American meat and fish supplies, and problems with contaminated fish and other food have been reported in other parts of Asia and in Europe.
China has strongly denied that its food exports are hazardous and has seemingly retaliated against criticisms in recent weeks by seizing American and European imports.
This week, China said it had impounded two shipments, of orange pulp and apricots, from the United States because they contained “excessive amounts of bacteria and mold.”
Earlier this year, regulators blocked imports of Evian water from France, saying bacteria levels in the water exceeded national standards.
Still, the government has moved aggressively in recent months to enforce food safety regulations and to weed out fake or contaminated food products.
Tuesday’s announcement, which appeared on the Web site of the country’s top food-quality watchdog, the General Administration of Quality Supervision, Inspection and Quarantine, has intensified concerns about rampant fraud in the food industry here.
Regulators said an investigation involving 33,000 law enforcement officials found illegal food-production and meat-processing operations, fake soy sauce and the use of banned food additives.
“These are not isolated cases,” Han Yi, director of the administration’s quality control and inspection department, told the state-run media. China Daily, the nation’s English-language newspaper, said industrial chemicals not intended for use in foods had been found in products as diverse as candy, pickles and seafood. Among the substances were dyes, mineral oils, paraffin, formaldehyde and malachite green, a chemical primarily used as a dye but also used as a topical antiseptic or treatment for parasites and infections in fish.
Regulators said they also learned that the potentially toxic chemicals sodium hydroxide and hydrochloric acid were being used to process shark fin and ox tendon.
These industrial chemicals are often corrosive, and are used in drain cleaners, detergent, fertilizer and surfboard wax, among other products.
Such discoveries have become common in China. In 2005, officials in south China found a company repackaging food waste and shipping it to 10 other regions. And just last week, officials said a company in Anhui Province, not far from Shanghai, was selling a two-year-old rice dumpling mix as fresh, according to the state-controlled media.
Experts here say that the country’s food regulations are not being enforced and that small-business men are willing to go to extraordinary lengths to increase profit.
Corruption and bribery are also part of the food and drug industry here.
The former head of the food and drug watchdog agency was recently sentenced to death for accepting bribes and approving the licensing of substandard drugs. And now, a Ministry of Agriculture official is on trial in Beijing for accepting bribes in exchange for endorsing food products.
But not all the problems stem from corruption or malfeasance. A. T. Kearney, an international management consulting firm, issued a report this week saying that one cause of food safety problems in China was inadequate logistics systems and a lack of cold storage.
The firm said China needed to invest about $100 billion over the next 10 years to upgrade its logistics and refrigeration abilities and to put new standards into effect.
In China, the study said, there are only about 30,000 refrigerated trucks for transporting food; the United States has about 280,000.
“In the entire supply chain there’s no common standard or world-class standard,” said Zhang Bing, who helped prepare the study. “There are a lot of things contributing to the food safety problem. There are companies putting chemicals into food. But there’s also a lot of spoilage.”