She came to New Zealand about two weeks ago and had been staying at the Base Hostel in central Auckland.
Police are growing increasingly concerned about a young British woman who went missing the day before her birthday in New Zealand.
A spokesman for the Foreign Office said it is providing consular support to the family in the UK.
He added: "Clearly this is a very stressful time for Grace's family and the longer she remains missing, the more our concern grows for her safety and wellbeing".
However she was travelling alone when she came to New Zealand about two weeks ago.
Ms Millane left the United Kingdom six weeks ago to travel the world after finishing university.
'It was what she wanted - she wanted to see the world, ' Mr Millane said. "At this stage we're still hopeful that we'll find Grace".
Beard said Grace had not been in contact with her family for a number of days.
Her phone is going straight to voice mail and has been silent on social media, Michael revealed.
Her family, from Wickford, near Basildon, said they spoke to her "most days", describing her silence as "completely out of character". The contact with us stopped on Thursday.
"The last contact anyone else had with her was on Saturday, when her roommates asked what she was doing with her day".
'Iran's missile program in compliance with UNSCR 2231'
Hook said United States discussions with the Europeans about missile sanctions are gaining traction. Those talks center on slapping penalties on companies and people involved in Iran's program.
Detective Inspector Scott Beard said officers had spent the past 24 hours trying to piece together her last known movements, who she has associated with and the circumstances of her disappearance.
'Her family member is coming out - obviously, they're distraught.
"She was in a very unusual place to stand, I would have thought a hitchhiker would have stopped on the left-hand side to get in the vehicle, she was on the other side".
Her older brother Michael Millane says police have found CCTV footage of her returning to her Auckland hostel on Saturday night.
Thousands of people have shared the post.
Police confirmed a missing person's report was filed today for Millane.
Her family reported her missing to New Zealand Police yesterday.
'We are unable to make further comment while police are investigating the matter'.
He is due to arrive in New Zealand from England tomorrow to help search efforts.
"It's unusual for her not to chat so we're really anxious - this is totally unlike her".
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