The authorities in the central Chinese province of Henan have closed 16 pig farms and sealed 134 tonnes of pork products after an illegal drug was reportedly used to produce lean meat, the official Xinhua news agency reported on Wednesday.                               
Some farms in the province, one of the country’s major pig breeding areas, are reported to have fed pigs with ractopamine, banned in the country, to promote production of lean meat, with the contaminated pork sold to the market and Henan Shuanghui Investment & Development Co Ltd the country’s top meat processor.   
Trading of shares in Shuanghui, based in Henan, was halted on Wednesday after the stock fell by the daily limit on Tuesday following the report by state television. 
Shunghui, which counts Goldman Sachs Inc among its investors, had already shut down the processor affected by the contamination, Xinhua reported.     
Ractopamine is frequently used by pig farmers in China, the world’s largest producer and consumer, as lean meat can be sold at a higher price.           
In a recent case in 2009, a court convicted 15 people in the southern city of Guangzhou after 70 people were poisoned by drug-contaminated meat.