The family of missing Canadian bushwalker Prabhdeep Srawn have called for Australian Defence Force personnel to be brought in to assist searching remote sections of the Kosciuszko National Park, after crews suspended search efforts in failing light on Thursday.
Rescue helicopters using state-of-the-art infrared scanners aided efforts around the Lady Northcote Canyon, Mount Sentinel, and the Opera House and Seamen's huts after new reports of a male voice being heard, 10 days after Mr Srawn was last seen.
The 25-year-old's parents, sister, brother-in-law and cousin maintained a sombre vigil at the National Parks and Wildlife office in Jindabyne, with local police monitoring specialised infrared scans and thermal imaging from two helicopters.
As many as 30 people on the ground failed to find any definite sign of the Bond University law student, who was last seen when he parked his car at Charlotte Pass Village on May 13. Crews continued searching until after 5pm on Thursday and were expected to recommence at 7.30am on Friday, amid failing hopes the operation would remain a rescue effort.
Two days after arriving from Ontario, Canada, Mr Srawn's sister Mandeep Srawn said her brother was the ''strongest person I know''.
''We don't want to endanger the life of anyone else looking for our brother which is why we think the Australian Army are the best option at this time,'' she said.
''They have a lot of men who are trained in survival and difficult conditions and are willing to come and look for our brother, who as a member of the Canadian Armed Forces, is really one of their own.''
Peter Hosking of the Kosciusko Huts Association has been supporting the family during the search, and on Thursday contacted Eden-Monaro MP and Defence Materiel Minister Mike Kelly to appeal for ADF involvement. So far the search is being conducted by police, SES crews and National Parks and Wildlife officers.
Ms Srawn said her brother's training as an army reservist included survival in temperatures reaching minus 15 degrees.
''We have been praying a lot, talking to family members and keeping in touch with the social media storm our relatives overseas have been running to put pressure on politicians in Canada and Australia,'' she said.
Snow is expected in the region in coming days with Perisher expected to drop to minus 3 degrees overnight. The Westpac Life Saver and Snowy Hydro Southcare helicopters will continue searching on Friday with Jindabyne police Inspector Peter Rooney co-ordinating ground efforts.