Osbourne, the 55-year-old wife of rocker Ozzy Osbourne, was due to join Simon Cowell, Louis Walsh and Dannii Minogue at the London auditions for the new season of the series June 12.

However, she has told the show's producers she will not be back, leaving her former bosses scrambling for a fourth judge, The Sun newspaper said.

"Sharon Osbourne has decided to leave 'The X Factor' after four fantastic years," ITV said in a statement issued to the newspaper. "ITV thanks her for her immense contribution to the show and for all her humor, compassion and energy. She has been a tremendous judge and mentor on the program, but we respect her wish to leave and wish her the very best with her future projects."