Aaron Klein made the claim after calling Palestinian terrorists to talk about a threat allegedly made against the former Beatle, who is to play his first Israeli concert Sept. 25.
Britain's Sunday Express reported last weekend that an Islamic militant leader in Lebanon had warned McCartney could be the target of a suicide bombing unless he canceled the historic gig.
However, Klein, WorldNetDaily's Jerusalem bureau chief and author of the book, "Schmoozing with Terrorists," said he called senior leaders from every major Palestinian terror organization in response to the claim and none of them knew who McCartney or the Beatles were -- not even when he sang to the terrorists popular Beatles songs such as "Yesterday" and "Let It Be."
The author said the threats against McCartney came from Omar Bakri, also known as Omar Bakri Mohammad, who was the leader of al-Muhajiroun, a London-based Islamist organization with the stated goal of creating a worldwide Islamic state starting in Britain.
Klein called Bakri a "notorious media attention seeker" who is "more talk than action."
He also said Palestinian terror groups "pay little to no attention to anything Bakri says or does. They don't take Bakri seriously."
McCartney has said he has no plans to cancel the concert.