A man is being spoken to over the alleged murder of UK tourist Grace Millane, police have confirmed. Her body is still missing.

Detective Inspector Scott Beard told media on Saturday that a 26-year-old man had been found at an Auckland address and was taken for questioning relating to the death of Ms Millane.

"Sadly the evidence we have gathered to this point in this inquiry has established that this is a homicide," he said.

"He is currently speaking to us in relation to the murder of Grace Millane."

He says the news comes as a devastating blow to Ms Millane's family.

"Grace is still missing and we want to find her," he said.

"We still do not know where Grace is. We're determined to find her and return her to her family."