Britney Spears is threatening to release video footage of one-time friend Paris Hilton in a lesbian romp with a mutual pal - if the socialite doesn't start treating her better. London's Daily Mail newspaper has been alerted to a letter Spears' camp has sent to Hilton, demanding The Simple Life star stops being rude to Britney and members of her entourage. They reportedly threatened to leak the footage, which shows Hilton in a compromising position with another woman, unless her attitude changes. A source says, "The letter warns Paris that if she continues being rude to people, the footage will be leaked online." Australia's Sydney Daily Telegraph reports the former friends fell out at Spears' 26th birthday parties in Hollywood at the weekend (01/02Dec07). But a source close to Hilton tells the Mail, "It's obvious Britney and her bratty pals are being silly. Paris laughed when she got the letter and said it was c**p." Hilton was the star of sex tape 1 Night In Paris, which was shot by her ex-boyfriend Rick Salomon - Pamela Anderson's new husband.