Details of the alleged $2 million (£1 million) extortion plot by Koral Karsan emerged when his supposed blackmail note was made public in court documents. His lawyer said that the document, which he filed in New York in support of a bail application, showed that Mr Karsan was pursuing a legitimate sexual harrassment claim against Ono, 73.

In the letter, Mr Karsan, 50, described himself as Ono’s “lover and confidant” for a decade-long relationship that had “deepened into a very emotional and physical one”. He threatened to sue for sexual harrassment, calling Sean, her son, Jan Wenner, the Rolling Stone publisher, and “Paul” — a possible reference to Sir Paul McCartney — to testify.

Mr Karsan told Ono that he had tapes “that will quite frankly astound the world”. He wrote: “If you want all of these pictures, recordings, e-mails, conversations and memories to vanish from the face of the Earth . . . send me a certified cashier’s cheque from a New York bank for a total amount of $2 million.”

The alleged material included a recording of Sean telling his girlfriend that John Lennon was “a wife-beating a**hole”. Mr Karsan also threatened to reveal “the story of you getting raped during World War II in a Japanese farm and the effects of this act on your relationships with men including John”.

Elliot Mintz, Ono’s spokesman, said that any intimation of a sexual liaison between Ono and Mr Karsan was “a clear, obvious, transparent shakedown”. Mr Karsan, who was arrested on December 13, faces up to 15 years in prison if convicted.

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