Grace Millane, who is from Essex, has been reported missing by her family, who say they have not heard from her in almost a week.
A British backpacker who was staying in an Auckland hostel has been missing for five days.
Millane's family sparked the investigation into her disappearance yesterday after they became alarmed when she didn't respond to birthday messages on Sunday.
They became anxious when she failed to contact them on her birthday...
She was last seen by her roommates at Base Backpackers Hostel on Saturday, and her brother Declan Millane says that most of her belongings had been left there.
"It's important that anyone who recognises Grace from this photo or saw her on Saturday night contacts Police immediately on 09 302 6970".
Various sightings have her wearing either black top, blues jeans and red sneakers, or a black dress with white shoes.
Before coming to New Zealand she travelled as part of an organised group through South America for six weeks.
Her older brother said it was completely out of character for her not to be in contact with her family.
Mr Beard said Ms Millane had a number of phones on her while in New Zealand. She's approximately 5ft 6in (168cm) in height, and 58kg.
"Where she was standing, it was really freakish and she was by herself, nobody around just a girl on her own", she said.
The radio silence was "unusual" for Grace, Declan Millane said.
He said they had been in contact with the British High Commission in Wellington.
Base Backpackers declined to comment to the Herald on Wednesday.
"We are working with the family in the United Kingdom and New Zealand police in relation to reports of a missing British national in New Zealand".
Members of Grace's family have shared appeals for information on Facebook and more than 20 police are working on the case in Auckland.