The brother of a young woman who has not been seen for five days has said it is completely out of character for her to not get in touch.

Grace Millane, 22, from Wickford, travelled to Auckland two weeks ago and had been in regular contact with her family via social media.

But her family became concerned after Grace failed to respond to birthday well-wishes on Sunday.

Speaking with the Echo, her brother Michael said: "We last spoke to her on Thursday morning and from there, we hadn't heard from her.

"It was her birthday on Sunday so we thought she would have been in touch.

READ MORE: Police searching for Wickford backpacker Grace Millane who has gone missing in New Zealand

"On Monday, it was weird that we hadn't heard from her so yesterday we started to make enquiries down the right channels and realised the last time she was seen was on Saturday by one of her room mates in a hostel she was staying at."

Grace had gone travelling after graduating from the University of Lincoln with a degree in Advertising and Marketing.

She initially flew out to New Zealand as part of an organised group but was travelling alone at the time of her disappearance.

Michael said: "She just wanted to see the world after graduating from university. She was just sight-seeing and travelling around New Zealand.

"Last time we spoke to her she was in good spirits and was enjoying herself. She didn't mention any specific plans for this week.

"It's really out of character for her to go this long without letting us know she is OK.

"My father is flying out to New Zealand this afternoon to help with the search."

Michael said the family are finding the uncertainty extremely difficult.

He added: "It's really tough - not nice at all. We all feel a bit helpless from over here. That's why my father is flying out there.

"If she gets this message, we would urge her to get in touch with us as soon as possible so we know she's OK."

A missing persons report was filed on Wednesday morning and police are investigating.

Tony McLeod, British High Commission Wellington consular manager, said the commission was aware of the missing person report.

He said: "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."

Ms Millane graduated from the University of Lincoln with a Bachelor of Advertising and Marketing in September.