Police in the Guangxi Zhuang autonomous region raided several illegal roast pork production sites in January, which sold unhealthy meat to restaurants, Xinhua News Agency reported on Wednesday.

Police in Nanning, the capital of Guangxi, first discovered two sites illegally producing roast pork from a residential building on Jan 15 after receiving a tip.

Police detained nine suspects and confiscated 650 kg of unhealthy pork.

Following clues provided by one suspect, police found another illegal production site on Jan 26 and detained 17 suspects, with 200 kg of pork confiscated.

The seized pork was made of the meat of pigs that died of illness, and had been sold to two well-known restaurant chains in Nanning.

Roast pork is an essential ingredient of rice noodles, a common food in South China.

The food quality inspection authority in Nanning launched a special campaign to inspect food stores from Jan 27.

At present, seven main suspects have been detained by police, the news report said.