Britney Spears has spent months undergoing intensive vocal training so she can sing live during her Las Vegas residency.

The Toxic superstar has previously been accused of lip-syncing during her high-energy shows, and recent reports suggested she would be miming along to her hits during her Sin City run, which kicks off in December (13).

A representative for the star has now shot down the gossip, insisting Spears will be singing live at her Britney: Piece of Me shows and she has spent months in training to make sure her vocals are strong enough for the two-year run.

A spokesperson for Spears tells the New York Daily News, "Britney will be singing... She is in vocal training - has been for months."