Rob Kardashian with sister Kim. (WENN.COM)

Porn queen Lisa Ann has been branded a liar by socialite Rob Kardashian's publicist after claiming she's romancing the 22 year old.

The X-rated actress, 37, who portrays former U.S. Vice President candidate Sarah Palin in porn films like newly-released You're Nailin' Palin, claimed she met Kim Kardashian's brother at the gym and the odd couple has been an item for a month.

She even went on record about the romance, insisting the age difference between her and Kardashian enhanced their sex life: "Rob treats me like his little teacher and we have a fun sexual relationship that is simple and carefree."

But a source close to Kardashian insists the porn star's claims aren't true.

The insider tells UsMagazine.com, "They did meet at a gym, but that's it... She wants a bit of fame right now. Rob is laughing it off."