Student and former Canadian Army reservist Prabhdeep Srawn parked his car at Charlottes Pass on May 13, and set off for a hike near Australia's highest mainland peaks. He has not been seen since.

The alarm was raised and a search began one week later, but was called off by police earlier this month as winter conditions set in. However Mr Srawn's family, including sister Mandeep Srawn, vowed to continue the search, and have since brought in volunteers and professionals to scour the rugged terrain surrounding Mt Kosciuszko.

The family has also offered a $100,000 reward to anyone who finds Mr Srawn.

Ms Srawn told Fairfax Media that up to 12 off-duty Canadian armed forces personnel would arrive in Australia on Sunday to join the search.

"They're not coming for the reward," she said. "They're coming because they can't leave one of their own out there."

She said the group was comprised of full-time, off-duty soldiers, some who had served on tours of duty in conflict zones like Afghanistan.

Ms Srawn also said a group of professionals were preparing to camp overnight in the mountains, before descending into Northcott Canyon with ropes and harnesses – an area she said the police did not comprehensively search.

By the weekend, the Srawn family expects to have up to 40 people actively searching the mountain.