Grace Millane's current profile picture on Facebook was uploaded on November 29 - two days before she disappeared.

There is "no evidence of foul play" in the case of a British backpacker who has gone missing in Auckland, police say.

Grace Millane, 22, hasn't been in contact with her family and friends for six days.

She was last seen by her roommates at Base Backpackers Hostel on Saturday, and her brother Declan Millane said on Thursday that most of her belongings had been left there.

Her social media accounts had also not been updated.

READ MORE: English backpacker missing in Auckland central

The radio silence was "unusual" for Grace, Declan Millane said.

NZ POLICE CCTV footage shows Grace Millane at SkyCity on December 1 wearing a black dress and white shoes.

"Being out of contact with family for this long is especially out of character for her."

Detective Inspector Scott Beard said police had no evidence of foul play, but were keeping an open mind.

The investigation so far had concentrated around Millane's movements since she arrived in New Zealand, he said.

She had travelled to the Bay of Islands on a trip, then arrived in Auckland on Friday.

She was last seen on Saturday about 7.15pm around SkyCity.

A "large focus" of the investigation had been examining CCTV footage, Beard said.

SUPPLIED Grace Millane hasn't been in contact with her family for six days.

"We are asking anybody who has been in contact with her or knows her to contact police.

"The longer this goes on the more concerning it is. At this stage we're still hopeful that we'll find Grace."

Meanwhile, her father had decided to fly to Auckland from Essex, in southeast England, on Wednesday night (England time) and was due to arrive in New Zealand on Friday.

SUPPLIED Grace Millane is believed to have met the man accused of murdering her through a dating app.

Grace Millane's other brother, Michael Millane, said she had travelled to South America with an organised group, before arriving in New Zealand two weeks ago.

It was her first time travelling solo.

The family have posted a plea on Facebook in the hope other travellers in New Zealand can help in the search. It has been shared thousands of times around the country.

Google Maps Base Backpackers is located on Queen St in Auckland's CBD.

Grace is described as a European woman with brown hair and brown eyes.

She is approximately 5ft 6in (168cm) in height, and 58kg.

British High Commission Wellington consular manager Tony McLeod said the commission was aware of reports of a missing British national.

"We are working with the family in the UK and New Zealand police in relation to reports of a missing British national in New Zealand.

"We are unable to make further comment while police are investigating the matter."

Various sightings have her wearing either a black top, blue jeans and red sneakers, or a black dress with white shoes.

Declan Millane said a few people had reached out to the family with potential sightings.

"There have been a few tips and we will be working through them."

Beard said Grace had not been in contact with her family for a number of days.

"This is particularly out of character, especially as it was her 22nd birthday on Sunday.

"We are working closely with her family at this time and a number of police staff are currently working on this matter."

Base Backpackers group operations manager Tom Cooney said the company's thoughts were with Millane's family.

"We have provided all requested information and CCTV footage to the police," he said.

"We are doing everything we can to help with the police investigation and will continue to do so for as long as necessary and we hope with the support of the Auckland community, Miss Millane will be found in the very near future."

Police are appealing for anyone who may have seen Grace on Saturday night or may have information on her whereabouts to contact police on (09) 302 6970.