The company that owns Kentucky Fried Chicken is facing new calls to stop using poultry that has been treated with antibiotics.
US consumer groups will deliver a petition signed by more than 350,000 people to Yum Brands on Wednesday.
KFC has already promised to limit the use of human antibiotics in its chicken by next year.
However, critics claim the policy effectively allows for routine use of antibiotics by its chicken suppliers.
The chain does not allow the use of antibiotics to promote the growth of poultry in line with federal government rules.
A KFC spokesperson said it was reviewing whether it could force suppliers to go beyond Food and Drug Administration rules on antibiotics usage.
“KFC is lagging woefully behind – diners around the country want KFC to step up,” said Lena Brook of the Natural Resources Defense Council, which is one of the groups delivering petitions to KFC headquarters in Louisville, Kentucky.
The action comes a day after Yum investors submitted a proposal asking that the company to speed up plans to stop using antibiotics in its meat.
Other Yum brand chains – Taco Bell and Pizza Hut – plan to cut the use of chicken treated with antibiotics by early next year.
Medical experts warn that the routine use of antibiotics to promote growth and prevent illness in farm animals contributes to the rise of drug-resistant “superbug” infections that kill at least 23,000 Americans each year and represent a significant threat to global health.
Fast food restaurants have become a focal point for change in the food industry by forcing suppliers to change their practices.
Last week McDonald’s said it had switched to antibiotic-free chickens in the US and Canada.
Chick-fil-A, another big US fast food chicken chain, has promised to use only antibiotic-free chickens by 2019.