The head of Wal-Mart's China business has quit, the US retailer said Monday, after Chinese authorities temporarily shut down over a dozen stores found to be selling pork falsely labelled as organic.

Ed Chan left "for personal reasons," Wal-Mart said in a statement, adding that Clara Wong, senior vice president of human resources division of the China operation, has also resigned.

Their departure comes after authorities in the southwestern city of Chongqing detained Wal-Mart staff and ordered the company to pay more than $420,000 in fines and other penalties.

The statement made no mention of the pork incident, which was widely reported in Chinese media.

Wal-Mart said last week it had shut 13 Chongqing stores for 15 days "so as to concentrate our efforts on completing corrective actions and taking all necessary steps to ensure this does not recur".

Wal-Mart opened its first Chinese stores in Chongqing in 2006 and now has 353 outlets in 130 cities across the country.

The shut-down of 13 stores in the city was an unusually harsh punishment for the mislabelling of food, which is common in China.

Chongqing authorities have punished the US retail giant at least 21 times for various problems, including selling food past its expiry date and false advertising, according to Chinese media reports.

The city is run by Bo Xilai, who has grabbed headlines for crackdowns on crime and corruption and for pushing nationalist sentiment by promoting the singing of Mao-era propaganda songs since he took charge at the end of 2007.

Scott Price, president and chief executive of Wal-Mart Asia, will serve as interim leader for China until a new head for operations is appointed, the company said.