They've got blonde hair, blue eyes, and occupy a special place in heart of generations of schoolgirls from every corner of the globe. But for years, Barbie and Ken appear to have been hiding a guilty secret.

The popular all-American toys turn out to have been created by "a full-blown Seventies-style swinger" with "a manic need for sexual gratification," who based their design on his favourite adult dolls, according to a new book.

Jack Ryan, whose five wives included the actress Zsa Zsa Gabor, is accused of staging wild orgies at his mansion in the exclusive Los Angeles suburb of Bel Air and surrounding himself with busty prostitutes hired because of their resemblance to Barbie.

The Yale-educated executive, who died in 1991 at the age of 65, used his office at the toy firm Mattel to take calls from a local "madame," and liked to pay for sex with "everyone from high-class call girls to streetwalkers," including "a very thin and childlike hooker".

In Toy Monster: The Big, Bad World of Mattel, the author Jerry Oppenheimer claims that Ryan, who also created the Chatty Cathy talking doll, spent decades hiding the seamy private life that might have sullied Barbie's squeaky-clean reputation.

More sinisterly, the book suggests that Ryan's colourful sexuality played a formative role in the design of the doll.

"When Jack talked about creating Barbie, it was like listening to somebody talk about a sexual episode," Mr Ryan's former friend, Stephen Gnass, reveals. "It was almost like listening to a sexual pervert."

Mr Oppenheimer quotes Gwen Florea, who was the voice of Barbie in a line of talking dolls, saying: "Jack once said he loved me being so tall so he could stick his nose in my boobs when he hugged me."

The revelations, which have yet to be dignified with a comment by Mattel, one of the world's biggest toymakers, come at an awkward time for Barbie and Ken, who celebrate their 50th birthday in March.