Simon Cowell reveals Britney's X Factor walk-off was for real

Simon Cowell feared Britney Spears would quit her post as a judge on The X Factor after she walked off the TV show set on the first day of auditions.

The pop superstar signed up for the reality series in a $15 million deal earlier this year (12), and she recorded her debut appearance in May (12).

Reports emerged at the time that Spears had left the set during her first few hours on the job, but insiders claimed she had only gone to use the bathroom.

Now Cowell has now admitted the excuse was a cover-up, and he was secretly worried about his new signing's future on the programme.

He tells TMZ.com, "No one is going to admit that on the first day your highest paid star after 20 minutes has walked off set. (She) had a moment on the first day where she said to me, 'I'm not sure I can do this.'"

Spears recently revealed to Elle magazine she was experiencing "panic attack after panic attack" as she battled nerves on her first day on the show.