NEW YORK CITY (Reuters) - The world's largest chain of fried chicken restaurants, KFC, is under fire for its use of antibiotics in its products.

An advocacy group, Natural Resources Defence Council, is pressuring the brand through a new campaign.

"KFC really needs to do its part to protect people from the raising threat of superbugs. It's their responsibility, and we believe that there's has been enough momentum in the chicken industry, where it should be possible for them to do this before too long," said Lena Brook, spokesman for the Natural Resources Defence Council.

KFC said in an email that its position on antibiotics is currently being reviewed to determine the viability for its suppliers to go beyond the FDA guidelines.

Some of KFC's fiercest competitors including McDonald's, Chick-fil-A, Chipotle and Panera, are already phasing out chicken raised with antibiotics, hoping to boost their appeal to younger, and wealthier customers by going antibiotic-free.

David Henkes, a food industry analyst at Technomic, said: "I think, this indicates sort of a broader change in what consumers are asking for, and a change in definition of health and wellness, and, I think, it's something that the restaurant industry is slowly trying to grapple with. And big chains, like KFC, are struggling with how to convert their whole system over to this changing consumer demand."

Shareholders of Yum Brands, KFC's parent company, had already launched a campaign of their own to force a switch.