KEY POINTS:
The brother of missing Israeli backpacker Liat Okin has arrived in New Zealand to join the search for her.
Itamar Tas, 26, said he was still holding out hope she would be found alive.
Ms Okin - who is also known as Liat Tas - has not been seen since failing to return from tramping the Routeburn Track on March 25.
An aerial and land search of the popular walking track has failed to find any sign of her.
She was reported missing by family members after she failed to contact them a week after setting out alone on a three-day tramp.
Mr Tas told The Southland Times his sister was a tough woman and would fight hard to stay alive.
Mr Tas, a media studies student, landed in Queenstown yesterday with his closest friend Joe Kariv, to join in the search.
They were accompanied by one of Israel's most high-profile professional mountain guides, Magnus Hilik, operations manager of Israel's search and rescue team.
Mr Hilik said he was sent by the Tas family's insurance company.
Police say fears for Ms Okin's safety are growing daily.
Outdoors experts have said Ms Okin was not an experienced tramper or well equipped and might have become disorientated on a section of the track described on a Department of Conservation website as "very exposed and extremely hazardous in adverse weather conditions".
"As every day passes concerns for her safety increase, obviously," Mr Hutt said. "You live in hope."
"The worst case scenario is that she's taken a wrong turn somewhere and we've just got to pinpoint where that could have been."
Mr Tas said it had been a stressful time for Ms Okin's family in Netiv Haasaa, just north of the Gaza Strip. They found out that she was missing only when Mr Tas' sister Shira Tas contacted the New Zealand police on Tuesday, he said.
"It is so stressful for my parents...but we're all trying to be positive because we're believing she's fine, we're worried of course that she's not in the best condition but we're all believing we're going to see her again."
Mr Tas and his friend were eager to join searchers in the Routeburn Track area to try and find his sister.
A team of about 20 police and search and rescue volunteers from Queenstown and Invercargill will today continue combing the rugged, sub-alpine areas of the Routeburn Track, north of the Mackenzie Hut, where Ms Okin was last seen.
Acting Senior Sergeant Steve Hutt, of Queenstown police, said searchers would now concentrate efforts on a number of side tracks.
- NZPA