Reports surfaced recently saying the two had a fallout once Barton began dating Cisco Adler, the ex-boyfriend of Hilton's best friend Kimberly Stewart. Other reports traced the purported feud to Barton's loyalty to Hilton ex-friend Nicole Richie.
Barton also was quoted in the Mirror claiming that the Simple Life star "seems to hate everyone around her age who is more successful ... She does steal people's boyfriends!"
The actress's rep told New York's Daily News that the actress was joking when she made the comments.
Hilton, however, is already striking back. Responding to Barton's comments through her Los Angeles-based rep Elliot Mintz, she tells PEOPLE: "I don't even know the girl. I could care less. It seems like she is the one who is trying to stir up a rivalry. I have never said a word about her in my life. But she seems to be spending a lot of time thinking about me."
Mintz also said of Barton's remark about Hilton's disparaging "successful" females: "I don't know of any girl around Paris's age, who is more successful. It seems to me a lot of celebrities are using Paris's name so they can get some ink and Mischa seems to be one of them."