Subway has become the latest foreign fast-food brand to be involved in a food safety scandal in China, after the US sandwich chain said it was investigating local media claims that workers at a Beijing franchise altered expiration dates on food ingredients.

Subway, which markets itself in China and overseas as a healthy alternative to traditional fast food, joins McDonald’s and Yum’s KFC in finding their brand reputation called into question in China because of allegations that staff at suppliers or franchises have used food beyond its expiry date.

Chinese media said one Beijing franchise of Subway changed expiry and production dates on meat, drink and vegetables to extend their use. Subway said on its Chinese website: “We have been made aware of these claims and are investigating them. This is not representative of the diligent Subway owners and sandwich artists in the Subway system. We will investigate and enforce our strict operational processes.”