Prince William's wife was pictured in London earlier this month (Feb12) wearing a coat with a synthetic fur lining, but the photo was seized on by officials at the International Fur Trade Federation.
Executives at the organisation posted the image on its Facebook.com page alongside a caption stating the duchess was wearing a "classy fur-lined coat".
But bosses at People for the Ethical Treatment of Animals (PETA) confirmed with the royal's office that the garment was fake fur - and founder Ingrid Newkirk has fired off a letter to IFTF boss Mark Oaten, who quit as a Member of Parliament in the U.K. in 2006 over a rent boy scandal.
In the letter, Newkirk threatens legal action if the image is not removed from the social networking website, writing, "The Duchess' office has confirmed in a letter to PETA that 'Her Royal Highness was not wearing fur. The coat was not lined with fur'. We therefore insist that you remove the photo from your social media page and issue an immediate public retraction of your claim.
"To state that the Duchess is wearing fur is not only false but offensive... To portray the new Duchess wearing something so blatantly cruel and contrary to her country's values is insulting."
Oaten resigned as a politician after it emerged he'd cheated on his wife with a male prostitute.