Property tycoon-turned-reality TV star Donald Trump has slammed the author of a new unauthorised biography for claiming he once had an affair with actress Robin Givens.

Trump states he feels "betrayed" by author TIMOTHY O'BRIEN, who was given intimate access to the billionaire's private world but was dismissed by the property king when his investigations started getting seedy.

Of the claims he bedded Givens, boxer Mike Tyson's ex-wife, Trump fumes, "It's not true."

He's also annoyed at cheap shots taken at his ex-wife Marla Maples in the book and by O'Brien's claims that the tycoon is not a billionaire and had to borrow money from his siblings to stay afloat.

He declares, "The book is not a very good book. Tim's not a very good writer."