Specialist rescue crews have joined the search for a bushwalker missing in dense and challenging terrain for 11 days.
As many as 50 specialist search operators from across NSW have been deployed to help find Victorian man Hadi Nazari, 23, who was last seen on Boxing Day.
The experienced hiker was descending the challenging Hannels Spur trail in NSW's Kosciuszko National Park with friends.
The three men were expected to meet at the Geehi campground but he failed to arrive.
The large-scale search involving NSW Police, the State Emergency Service, National Parks and Wildlife Service, NSW Ambulance, and volunteers was launched when Mr Nazari failed to meet friends at Geehi campground.
The operation has intensified, with six Rescue and Bomb Disposal Unit specialist police officers winched into the dense bushland by aircraft to access remote areas more quickly.
Six specially trained volunteers were to camp to further extend the search, which resumes on Sunday.
More than 300 people had searching for Mr Nazari since he went missing, Riverina Police District Acting Superintendent Jill Gibson said on Saturday.
"Our focus and efforts continue to be finding Hadi and returning him to his family," she said.
She said the weekend's hot and humid conditions added to difficulties searchers faced.
Rubbish and hiking poles believed to belong to Mr Nazari were found near the Kosciuszko River on Tuesday, narrowing the search area in the challenging terrain of the Hannels Spur Trail.
Experienced bushwalking guide Doug Chatten said the area was unforgiving, particularly for anyone who ventured off track.
"If you're off the track, it's bloody tough country," Mr Chatten told AAP.
"It's no easy walk, that's for sure ... you'd be a hard person to find."
The Hannels Spur trail, with its 1800m elevation change, is one of Australia's most difficult bushwalking routes.
