Shares in hog processor Zhongpin recovered some lost ground after the group distanced itself from pig doping claims – involving a drug associated with athletics cheats - which have drawn in China's largest meat processor.

Stock in New York-listed Zhongpin rose 1.1% in early deals - recovering some of the 7% lost in the previous session after a state broadcaster alleged that several farms were using clenbuterol hydrochloride, or ractopamine, as an additive to producer leaner pigs.

Chinese authorities investigating the claims have closed 16 pig farms and sealed 134 tonnes of pork products, state news agency Xinhua reported on Wednesday.

And Henan Shuanghui Investment & Development Co, the country's top meat processor, apologised for the role of its Jiyuan Shuanghui subsidiary in selling the tainted pork.

Henan Shuanghui shares slumped 10% on Tuesday on the Shenzhen exchange on news of its involvement, before a trading suspension which remained in place on Wednesday.

'Strictest inspections' 

However, Xianfu Zhu, the Zhongpin chairman and chief executive, said that the company's meat was processed "under the strictest quality inspections", in facilities which met national standards.

"As standard operating procedure, if contaminants or illicit or poisonous chemicals, such as the lean drug clenbuterol, are found to exist in the processing lines, Zhongpin immediately conducts harmless disposal to eliminate all possibly contaminated material and contaminates," the group said.

"This standard practice is rigorously followed."

Furthermore, the group's hog suppliers were "mainly standardised live hog breeding farms and brokerages" which shared its "commitment to the strictest quality assurance".

Banned additive 

Clenbuterol acts to produce leaner meat by increasing metabolic activity – a property which has also gained it popularity as an, illegal, performance enhancer among sportspeople.

Athletes banned after testing positive for the drug include UK hurdler Callum Priestley and US swimmer Jessica Hardy, while Spanish Tour de France champion Alberto Condator had a suspension reversed.

However, it can produce side effects such as nausea and palpitations.

Clenbuterol already has a history of food poisoning in China, including a case involving more than 300 people in Shanghai five years ago.

The country is, however, attempting to improve on its mixed reputation in food safety, which included the 2008 melamine scandal in which tainted milk killed six children, and was alleged to have made a further 300,000 people ill.