The former Westlife star sends messages to fans on the site using the handle @BrianMcFadden, and he is keen to have the unofficial @brianmcfaddenn page shut down, reported New magazine.
McFadden revealed that he is offering up 645 pounds to anybody who can help him find the person behind the fake page.
In a post on the site, he wrote, "Anyone who knows who owns and runs the hoax Twitter account @brianmcfaddenn let me know. 645 pounds reward if you do," he posted.