State media in China reported that police have arrested nine people for selling pigs that were fed a banned chemical, in a case that resulted in at least 70 people being made ill.
Charges are pending against a total of 15 people in the case that occurred in southern Guangdong province in February, with the other six still yet to be arrested, Xinhua news agency said.
The chemical in question was clenbuterol, a drug often given to people to treat asthma, but also commonly used to cut body fat.
Farmers in China have been known to feed pigs clenbuterol to reduce their fat, but it is banned as a food additive because it can be fatal for humans.
The up to 70 victims suffered from stomach pains and diarrhea after eating the tainted pork, the report said.
One of the worst cases involving clenbuterol occurred in Shanghai in 2006 when 336 people were hospitalized after eating pig meat or organs contaminated with the drug, state media reports have said.
The reputation of China's poorly regulated and corruption-plagued food industry has taken repeated hits in recent years, with people dying from eating tainted products at home and contaminated exports being found overseas.
Six babies died of kidney problems and 300,000 others fell ill last year after being fed milk powder tainted with a chemical normally used to make plastics.