Officers in Dorset work with police in New Zealand over claims girl was sexually assaulted by her father

The forces have launched a joint investigation into the allegations.

The girl's parents are separated and embroiled in a family court dispute in London.

She lives in England with her mother and her father lives in New Zealand.

The girl had made the complaint when in England, telling a relative that her father had sexually assaulted her when she was with him in New Zealand.

Detail of the investigation has emerged in a ruling by a London judge who has overseen the latest family court hearing.

Mr Justice Holman said New Zealand police will take the lead. Any interview with the man, and any prosecution, will take place in New Zealand.

The couple had become involved in family court litigation after the woman and her daughter left the country and travelled to England.

The man has asked a judge in London to order the girl's return to New Zealand, the court heard.

While the family involved cannot be identified, the judge indicated the little girl and her mother have links to Dorset as the complaint has been passed to the county's police force.