A reported case of a "missing tramper" was actually a serial absconder who terrified elderly hikers and fled into deep bush to avoid armed police out hunting for him.

Police spoke on Monday about a successful search and rescue mission for a tramper missing in remote, "unforgiving" south Westland country over the weekend.

They made no mention about an aggressive individual who sparked a dramatic high-country chase.

However, a tramper who encountered the missing man at Welcome Flat Hut in Copland Valley was so troubled by the police's sanitised version of events given to media, that he contacted the Herald to tell his side.

It involved a stranger's bizarre actions, threatening language, and absconding when police were called, taking off into the bush, crossing a high and freezing Copland River and avoiding a police dog, search and rescue (SAR) tracker dog, helicopters, and thermal imaging.

The man, who has a history of absconding and who the Herald has decided not to name due to concerns over his mental health, had been camping in a tent directly beside the Copland Pass track to Welcome Flat Hut.

On Friday, a group of trampers, who know the area well, came across him 15 minutes into their planned weekend in the area, and found him chatty and calm.

Later, when they were at the Welcome Flat Hut, the man joined them, and after initially being friendly, albeit "slightly manic" and making odd comments, became aggressive during the evening.

Police officers get ready to search for the man. Photo / Supplied

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One witness, who spoke to the Herald, said that an elderly group of three people had asked the man to quieten down when he started screaming and kicking their door as they barricaded themselves inside.

"He was trying to kick in the door," the witness said.

"He was anti-authority – he just didn't like being told what to do."

After managing to calm him down, the man then stayed up all night, the witness said.

When the man's erratic actions continued the next day, cleaning and digging trenches that he filled with coal – and the elderly group left - a DoC hut warden was informed, who tried to reason with the man, before phoning the police later on Saturday.

Anyone who challenged him were called "Nazis" and "fascists", the witness said.

Three police officers, armed with Glocks and Tasers, flew in via helicopter on Sunday morning, reportedly telling the tramping group that they knew who the man was and that they should try to leave him alone.

But at the sound of the chopper, the man took off.

A fruitless search ended and one police officer flew out, while two officers waited for him to return to the hut.

When he did come, the witness says other trampers tried to alert the police that he was back, which spooked him and he took off again.

He was chased by police but after escaping across the strong-flowing, cold river, the chase was abandoned for the day.

Another helicopter arrived with more police officers, a police dog and thermal imaging gear, along with a SAR team.

The police dog got a scent of him and another pursuit began.

The man was eventually found around midday on Monday near Douglas Rock Hut, about 10 hours from the road and four hours from where he was initially seen.

He was airlifted by Greymouth's rescue helicopter and is now receiving medical attention, West Coast Area Commander Inspector Jacqui Corner said.

The tramper said he hopes that the man gets the help he plainly needs.