Britney Spears has banned pretty female staff from working on the US 'x factor'.

The 'Toxic' singer - who joined the panel of the reality TV show as a judge this year alongside Demi Lovato, Simon Cowell and L.A. Reid - has reportedly told producers she doesn't want any attractive women working backstage while she is on the show as they make her feel insecure.

A source told the Daily Star newspaper: ''Britney has stipulated that none of the female backstage staff working with her are too pretty or stylish.

Britney recently claimed she is a ''very subtle'' 'X Factor' judge and tries to be constructive in her advice for the auditionees.

She said in a promo clip for the show: ''So far everything has been so fun for all of us.

''Everything is like a new experience for me, so it's a lot of fun and the talent has been amazing.

''I feel like my judging style is very subtle. I try to use constructive criticism.''

Despite saying she is ''subtle'', Britney - who has been described as an ''incredibly tough'' judge - is seen in the video dispensing some harsh words to one contestant.

She tells the hopeful: ''I wanna know who let you on stage.''