A wide-scale sweep by a private rescue crew has so far failed to find any trace of 30-year-old Jordan Yap, who last made contact with friends and family on September 14 ahead of a planned 10-day solo trek along Peru's Huayhuash mountain range, 400km north-east of Lima.
He was last seen near the beginning of his trek across the Cordillera Huayhuash circuit, which is regarded as a challenging, high-altitude trek through the remote Andes mountains.
Regarded as a very experienced hiker by friends and family, the Melbourne man failed to make contact on Wednesday, his estimated return date.
He also failed to check back into the Krusty Hostel in Huaraz, where his luggage remains stored, and missed a scheduled flight from Lima to Cusco on Thursday.
"It's really uncharacteristic of him to not have communicated at any point in his journey if he had the chance to," long-time friend Kevin Nguyen told AAP.
"It is a very popular trek, where you might have 200 to 300 hikers and guides per week during the busy season, so it is very uncharacteristic that no-one's seen him since day one or day two."
The avid trekker misplaced a satellite beacon he was travelling with days before he set off on the 120km hike, raising further concerns.
Local mountain rescue organisation Socorro Andino Peruano has been hired by Mr Yap's family to help with the search.
His loved ones are holding out hope the rescue group, which recently rescued a Canadian trekker from the same trail, will be able to find him safe.
"Time is of the essence ... because ultimately, as much as we were saying he's been missing since the 23rd, he's had no contact with anyone since the 14th," Mr Nguyen said.
Rescue crews completed their biggest day of search operations so far on Saturday (Sunday morning AEST), scouring various trails on the circuit to no avail.
"I know Jordan likes to orienteer and navigate and he's quite an adventurer himself, so I wouldn't be surprised if he tried an alternative route," Mr Nguyen said.
Mr Yap had been planning the trek for more than a year and had recently bought a GPS watch to allow for offline maps to guide him on the hike.
"He was telling everyone about how he was ready to go on a big hike like this, (he was) really excited," Mr Nguyen said.
He was last known to be wearing a white jacket, green sunshade sweater and grey pants.
The experienced trekker was believed to be carrying a 40-litre hiking bag, Durston dome tent and hiking poles.
Family and friends are urging the Australian government to work with Peruvian officials and local authorities to mobilise further resources in and around the rugged region.
The Australian embassy in Peru is helping his family.
The Department of Foreign Affairs and Trade has been contacted for comment.
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