A television expose showing improper meat handling by a supplier caused "significant, negative" damage to sales at its KFC and Pizza Hut restaurants in China over the past 10 days, US-based Yum Brands Inc said on Wednesday.

"If the significant sales impact is sustained, it will have a material effect on full-year earnings per share," Yum said in a regulatory filing.

Shares in Yum, which counts China as its No 1 market, tumbled 6.2 percent on the New York Stock Exchange in extended trading, down $4.50 to $68.50.