A New Zealand teen was forced to marry her boyfriend's father and consummate the marriage after the groom gave her parents a pig and some mats as a dowry, according to a report on Sunday.

The girl's mother and a man understood to be her stepfather have been charged with detaining her, "allegedly to force her to be the groom's wife and to force her to have sex with him", the Sunday Star-Times said.

The mother is also charged with assaulting her daughter twice over the marriage issue.

The report said the girl, of Tongan descent and believed to be about 17 years old, did not want to marry the man but an agreement was reached between the two families and she was obliged to honour it.

Her family was given a dowry of a large pig and expensive mats.

On her wedding night, the girl ran away to her boyfriend, understood to be the groom's son.

It was then that she was allegedly assaulted, abducted and taken back to the matrimonial home to perform her duties as a wife, the report said.

Neither the girl nor her husband could be reached for comment but her mother told the newspaper: "My family's problems are gone... I don't want to say anything."

The mother and her husband are due to reappear in court later this month facing six charges, the most serious of which carries a maximum sentence of 14 years' jail.

- AFP