Separately, the Health Ministry reported 3,503 cases of food poisoning nationwide in the second quarter of this year, including 70 deaths. Most fatalities occurred in private homes, with poisonous plants and animals blamed in 37 percent of the cases and chemical contaminants in 27.8 percent, the ministry said.

Wholesale pork prices were nearly 75 percent higher in July than a year earlier, prompting widespread reports of butchers selling meat from diseased pigs or injecting water into their product to increase its sale weight.

The higher prices are blamed on a shortage of the meat, partly because of an outbreak of blue ear disease, which has killed tens of thousands of pigs in recent months.

"Industrial and commerce departments at all levels should strike hard and strictly fight against the practice," said a notice posted on the government's Website issued by six ministries, including health, agriculture and public security.

The mandate also said it was strictly forbidden to add illegal additives to pig feed, and it pointed out that anyone caught selling tainted meat or using banned chemicals will be punished.

Pork is the meat of choice for most people in China, where city residents ate an average 19 kilograms per person in 2006, the government has said.

The Chinese government has in recent weeks taken steps to tighten restrictions and surveillance over the country's food and drug industries following international concern over its exports.