Search and rescue authorities in New Zealand are still hopeful that a massive search effort will turn up missing Israeli tourist Liat Tas-Okin. Four search teams, helicopters, dogs and a rescue expert provided by the Israeli government are working on the hunt for Okin, 35, who has been missing for three weeks. Queenstown's Senior Sergeant Hutt of Search and Rescue said Okin, from Netiv Ha'asara near Gaza, was last seen on the Routeburn Track - a route which traverses the alpine mountains of southern New Zealand. It was reported at the time of her disappearance she was only lightly clothed, wearing only a red hoodie with zip-up front, jeans and a backpack. She was however "completely overloaded" with food according to Christchurch-based Habad Rabbi Oren Raz. He said that if anyone could survive, she could. "She is the kind of person who could last for a very long timeâ€¦ she is a real fighter and she will never give up," he said. Deteriorating weather conditions in the alpine area over the past couple of days have hampered search efforts. Specially trained police dogs were to be brought in to help. Hutt said they had three Squirrel helicopters engaged in an aerial search, with the pilots having clocked up more than 30 hours of flying time. The Israeli government has also given assistance. Okin's brother, Itamar Tas, has also flown in to help in the search.