One of Britney Spears' former music video co-stars has threatened to file a lawsuit against the singer for injuries she sustained on the set.

Dawn Noel is planning to file a lawsuit, according to Tmz.com, claiming Spears accidentally slapped her as they were rehearsing a dance sequence for the Work B**ch promo in August (13).

Noel claims the unbalanced pop star smacked her in the face with such force that everyone in the room heard a cracking sound.

The dancer reveals the slap left her in excruciating pain, but Britney simply apologised and then continued the rehearsal.

Noel claims a doctor later told her she had sustained a nasal bone fracture and needed surgery.

She claims Britney's handlers promised to pay her medical bills, but she's still waiting for compensation.

Tmz.com reports Noel's lawyer Sark Ohanian will file a lawsuit on Monday (05May14).