A regional doctor who founded the Australian Anti-Paedophile Party is being sued by a man who claims he has been falsely branded a paedophile.

William Russell Massingham Pridgeon, a Grafton GP, set up the political party last year and wrote on its website he had turned to politics as a last resort after trying desperately to protect his wife's son from what he claims is his biological father's paedophilia.

The party's seven candidates are contesting the federal election but their efforts have been derailed after the biological father, Howard Furner, launched defamation proceedings in the Supreme Court.

Mr Furner was not named on the Australian Anti-Paedophile Party's website but Dr Pridgeon made references to him by describing his despair and frustration after the boy was not removed from his father's care.