Britney Spears has hit back at her lip syncing rumours, insisting that she is undergoing "grueling" vocal training for her upcoming Vegas 'Britney
Her spokeswoman told Metro.co.uk that she wants to make sure she can handle 48 live concerts when her shows kick off at the 4,600-seater Planet Hollywood venue in December.
Spears will rake in 200,000 pounds a night for her shows.
Earlier she was accused of being paid a lot of money just to lip-sync.
The insider told the New York Daily News that the 'Toxic' hitmaker hasn't sung live for a couple of years.
