NSW Police say they are hopeful that a missing hiker is still alive after he disappeared in Kosciuszko National Park 12 days ago.

Hadi Nazari was last seen by his mates at 2.30pm on Boxing Day when he was heading down the Hannels Spur Trail at Geehi, between Khancoban and Thredbo.

He stopped on the trail to take photos and went missing shortly after.

NSW Police Superintendent Andrew Spliet said today that he had taken camping gear with him for a short camping stint before he was meant to meet his friends at the Geehi Campground, but he never showed up.

The search party found a number of items belonging to Nazari on Sunday at a makeshift campsite, including a camera and lighter.

They had also found a hiker pole and rubbish in a separate area on December 31, which are also believed to belong to Nazari.

“He had a tent and a sleeping bag as well as a small bottle of water, a camera case that he had, [he was] set up for a limited time of camping,” Spliet said.

“We located some rubbish and a hiking pole… we also discovered a campfire area, as well as a lighter, camera and camera case.”

Spliet said that the items were found a far distance from each other, suggesting Nazari is moving around the “dense, thick” bushland.

He said crews remain “hopeful” that the 23-year-old student from Melbourne is still alive.

“We’re very hopeful [that he’s alive] we also rely on experts who have expert knowledge on survivability in these areas,” Spliet said.

“He’s got access to water, that’s the reason we’re still out here… he is aware of these surroundings, he’s got some capability to protect himself from the elements.”

“We will continue with the search until we are content that we’ve covered every area that we can.” 

The search party has expanded to involve several agencies including NSW Police Rescue and Bomb Disposal Unit and Riverina Police District officers, the SES, National Parks and Wildlife Service, NSW Ambulance, RFS, VRA Rescue NSW, PolAir and Westpac Lifesaver.