Britney Spears has been sued for allegedly breaking her backing-dancer's nose during rehearsals last year.

Dawn Noel has filed a lawsuit against the 32-year-old singer after she accidentally whacked her in the face while practising for her 'Work Bitch' music video at a studio in Woodland Hills, Los Angeles, on August 19, 2013.

Ms Noel claims the 'Hit Me Baby One More Time' hitmaker arrived two-and-a-half hours late for rehearsals ''in a dishevelled and confused state''.

She went on to state the choreography for the dance was ''fairly basic'', but Britney appeared to be having ''difficulty learning the moves and following simple directions.''

Ms Noel claims she was standing to the side of Britney when the star ''twirled in an unbalanced and reckless manner, arms extended out to her sides and forcefully backhanded'' her square across the face.

The lawsuit, obtained by E! News, alleges that there was a ''cracking sound'', known immediately to be Ms Noel's nose, that was heard by other dancers.

Britney allegedly said sorry after the incident, before continuing with the dance routine.

Ms Noel sought medical advice half an hour later and was told she had a nasal fracture that would require surgery.

The lawsuit states that Britney and Reign Deer Entertainment agreed to pay for the medical bills, but Ms Noel was informed months later that wasn't the case.

Ms Noel is suing for serious physical and emotional damages and is demanding a jury trial.