Prime Minister Helen Clark and fellow trampers fought to revive their mountain guide last night after he suffered a suspected heart attack.
But their prolonged efforts failed to save 59-year-old Gottlieb Braun-Elwert.
The group was tramping in mountains near Lake Tekapo in Canterbury.
Search and Rescue had last night reached the hut in the Two Thumbs range to collect the body of Mr Braun-Elwert and evacuate the party of seven.
Mr Braun-Elwert collapsed about 4.30pm.
The party included Helen Clark, her husband Peter Davis, Energy Minister David Parker and Tourism Minister Damien O'Connor.
Members of the party carried out CPR on Mr Braun-Elwert for about three hours until they were advised to stop by ambulance staff.
They contacted emergency services by cellphone.
Mid-south Canterbury area commander Dave Gaskin said a helicopter sent from Christchurch had been unable to reach the location because of bad weather.
A spokesman for the Prime Minister said: "The Prime Minister and Peter Davis are deeply shocked and saddened by the sudden tragic death, and their thoughts are with the family."
The spokesman said Helen Clark and the members of her party were in no danger.
The Prime Minister holidays in the area for a few days every year, and often tramped with Mr Braun-Elwert.
She and Dr Davis are keen skiers and trampers, and often holiday in remote areas.
Mr Braun-Elwert was a professional mountain guide for 34 years.
He had his own business, Alpine Recreation, at Lake Tekapo.
He was the first person to climb all New Zealand's 3000m peaks in a single winter season.
His other notable climbing achievements included making the first ascent of the entire Peuterey Ridge of Mont Blanc in 1973, a 1993 winter ascent of Cerro Fitz Roy (Supercanaleta) in Patagonia, three winter crossings of the Patagonian ice cap in 1994, 1995 and 1996), 26 ascents of Mount Cook and eight ascents of Mount Tasman.
Mr Braun-Elwert was also a nuclear physicist, who immigrated to New Zealand in 1978.
He had an MSc in nuclear physics and was a founding member of a "physics and ecology" workshop at the University of Munich.
The group researched the interrelation of energy consumption, population density,and environmental impact.
He was a member of the New Zealand Alpine Club, the German Alpine Club, the Royal Forest and Bird Protection Society and the Canterbury-Aoraki Conservation Board.
He pioneered many ski touring routes in Europe and was one of New Zealand's leading climbers and guides.
He served on the first round of a ministerial reference group looking into issues of public access to waterways and rural backcountry.
His interests also included nature photography and filming.
He campaigned to have "natural quiet" recognised as a resource which needed to be protected, particularly where it was threatened by helicopter noise.
He was married to Anne Braun-Elwert, a co-director of Alpine Recreation.
She climbed Mount Cook in winter, and joined her husband on ski tours, tramping trips and on two Patagonian ski traverses.
She has a bachelor's degree in English and was formerly a secondary school teacher.
Their daughters Carla and Elke are professional ski instructors.
At the age of 14 each girl in turn became the youngest person to have climbed Mount Cook.