Two animal welfare experts resigned as advisors to fast-food chain KFC after the company asked them to sign an agreement preventing them from speaking publicly about its policies on such issues as animal slaughter.

Temple Grandin of Colorado State University and Ian Duncan of the University of Guelph in Ontario, Canada, say they stepped down from KFC parent Yum Brands Inc.'s animal welfare committee this week after being sent the agreement, which would have required them to refer all media inquiries to KFC's corporate headquarters.

Both Grandin and Duncan are used to preserving confidentiality with respect to suppliers and pricing information. But no other company, including KFC, has ever asked them to sign an agreement to refrain from speaking to the press.

KFC spokeswoman Bonnie Warschauer says the contract was no different from previous confidentiality agreements members of the animal welfare committee have signed. She didn’t specify why the company was asking committee members to sign the agreement again, and added that she did not know whether other members of the committee had signed it.

The company is working on a new agreement with both Grandin and Duncan under which they would serve as technical advisors to the company.