The inventory from previous purchases has already been sold, according to the investigation.
KFC said Tuesday that it stopped buying raw chicken from Shandong Liuhe in August. The company said it uses its own criteria to test raw chicken supplies for drug residue, as well as checks its suppliers' feed and drug records annually.
China's poultry raising regulations state that chickens may not be given drugs within one week of being slaughtered.
However, poultry farmers in Shandong told reporters that their chickens might die within two days in crowded chicken houses if they were not given antibiotics.
Beijing-Zhengzhou high-speed railway to start service on Dec. 26