The name of the 27-year-old man charged with Millane's murder is being kept secret for now by court order.

Millane's body was discovered in a forested area near Auckland in December a week after she was last seen in the city.

She was travelling in New Zealand as part of a planned yearlong trip abroad.

Her death struck a deep chord in New Zealand, which prides itself on welcoming tourists and where many young people take gap years to travel.

Prime Minister Jacinda Ardern summed up the national mood at the time in an emotional news conference.

"There is this overwhelming sense of hurt and shame that this has happened in our country," Ardern said.

Millane had been in New Zealand for less than two weeks when she went missing.

Her father, David Millane, said last year that before she went missing, his daughter had loved her time in New Zealand judging by the number of pictures and messages she'd sent.

"We all hope that what has happened to Grace will not deter even one person from venturing out into the world and discovering their own overseas experience," he said in a statement.

New Zealand's judicial system sometimes suppresses the names of people facing charges on the basis that they won't be able to get fair trials if they are named.

But the Millane case has highlighted the difficulty of courts maintaining secrecy in the internet age.

Last year, some British media elected to name the man in defiance of the New Zealand court orders.

Search giant Google then emailed the name to some users who were signed up for alerts on what was trending in New Zealand, resulting in a rebuke from Justice Minister Andrew Little.

Google then suspended the service in New Zealand.

Australian Associated Press