Britney Spears has quit 'The X Factor' USA.

The 'Hold It Against Me' singer - who acted as a judge on the second series of the FOX reality TV show alongside Simon Cowell, Demi Lovato and L.A. Reid - has decided not to return to the next season of the singing contest because she wants to concentrate on her own music career.

A source told gossip website TMZ: ''Britney loves Simon, she likes Demi Lovato but her thing is music.''

Britney - who was on a one-year $15 million contract and whose act Carly Rose made it to December's grand final - is currently in the studio working on her eighth studio album and after she completes the LP, the mother-of-two is considering going on tour again.

It was recently claimed the 31-year-old blonde was going to be given the axe from 'The X Factor' after disappointing producers with her ''low energy'' and providing ''boring'' feedback to contestants.

An insider said: ''Britney will get the boot. Producers wanted her for the long haul, but it isn't working. They paid all that for her to say 'amazing' and offer half-claps.

''Simon wanted crazy Britney, but he got boring Britney.''

As well as Britney leaving, producer L.A. confirmed last year, he won't be returning for a third series.