JERUSALEM – Did you hear the one about the Jewish doctor who helped the Saudi crown prince make it big-time with ravishing Riviera babes?

Well, it’s no joke.

A prominent Israeli urologist regularly slipped into Saudi Arabia dressed in Arab garb to secretly treat King Fahd, who died yesterday, and other royal princes for their impotency problems.

Dr. Moshe Many told The Post he made frequent top-secret medical missions to Saudi Arabia – and to the posh playgrounds of the randy royals – to help them overcome a problem they had bedding European women.

His visits, which started in 1978, when Fahd was crown prince, were arranged by Saudi gazillionaire playboy-arms dealer Adnan Khashoggi shortly after the Camp David peace accords.

The royals “didn’t know I was an Israeli. They thought I was Italian,” Jerusalem-born Many told The Post.

He said the princes had an inferiority complex that rendered them impotent when they tried to have sex with European women.

He helped them out by prescribing a prosthesis, he said.

Many, 70, said he ended his clandestine doctoring after Fahd was crowned king in 1982.

Asked what Fahd would have done if he had discovered he was Israeli, Many said, “Once he had accepted me as a physician, he himself would have taken care of it, and it wouldn’t have become known.

“But he never learned it,” he said.

Although Israeli officials were aware of his undercover urology, Many insisted, “I was not going there to spy or to get information.”