LONDON, United Kingdom — British fashion designer Stella McCartney says she'll stop using wool from an Argentine supplier amid concerns about the treatment of sheep.

McCartney, whose brand doesn't use leather, fur or animal skin, says in an Instagram post that she will no longer use wool from Ovis 21 after People for the Ethical Treatment of Animals released a video showing the alleged mistreatment of sheep. McCartney says only one of 26 ranches used by Ovis 21 was involved, but that "is one too many."

"I am devastated by the news but more determined than ever to fight for animal rights in fashion and monitor even more closely all suppliers involved in this industry," she wrote.

Ovis 21 says it is dedicated to regenerating grasslands and specialises in "holistic management."