Britney Spears will reportedly lip-sync her way through her Las Vegas residency show.

The 31-year-old pop star has signed a two-year deal for a series of concerts at the Planet Hollywood Resort and Casino in the US city - where she is rumoured to earn $310,000 for every show - although she may not actually sing.

A source told the New York Daily News newspaper: ''Britney does not sing. She is being paid a lot of money to lip-sync. Her fans are none the wiser, but it is disingenuous of her to take their cash and not deliver a proper performance.''

The blonde beauty is planning on performing a sets packed with hits from across her career during the 'Britney: Piece of Me' shows, which kick off on December 27, but there are fears her lip syncing may upset fans in the 4,600-capacity venue.

The source added: ''She hasn't sung live for a couple of years. If the crowd thinks they are being cheated then there is likely to be an uproar.''

However a representative for the star denies the source's allegations, saying: ''Britney will be singing. As stated before, she is in vocal training - has been for months.''