Britney Spears has confirmed her 'X Factor' departure.

The 'Toxic' singer quit her role as a mentor on the Fox show in order to focus on her music career and admitting watching the contestants perform every week helped her to make the decision to leave.

She explained in a statement: ''I've made the very difficult decision not to return for another season. I had an incredible time doing the show and I love the other judges and I am so proud of my teens but it's time for me to get back in the studio. Watching them all do their thing up on that stage every week made me miss performing so much! I can't wait to get back out there and do what I love most.''

Meanwhile, it has been claimed Britney, 31, is in ''serious talks'' for a residency in Las Vegas.

According to gossip website TMZ, ''Britney and her people are talking about establishing residency for the singer in Sin City and are also in talks with one of the hotels to do a big, nightly show.

''Negotiations are with one of the Caesars group properties, and they have been wooing her for awhile.''

''There is a lot of interest in Britney's camp over a Vegas move, and a lot of interest on the Vegas side of headlining a show.''