Police in Dunedin say an officer has a broken nose because a man she was arresting head-butted her after she had handcuffed him.
They say the constable was called to a domestic dispute at a home in Mosgiel late on Monday night and arrested the man for assaulting a woman at the house.
Inspector Greg Sparrow says the man, who was being led to a patrol car when he attacked the constable, is facing charges for resisting arrest and injuring, as well as for assault.
Mr Sparrow says the injured constable was treated in hospital and will spend the next few days recovering.
He says the incident shows that the daily work of police officers is often dangerous.