WELLINGTON - A JAPANESE climber was plucked alive by rescuers from New Zealand's highest peak shortly after dawn on Friday, but his companion was found dead, searchers said.

Tokyo residents Hideaki Nara, 51, and Kiyoshi Ikenouchi, 49, had been trapped for a week by bad weather on a ledge of the Empress Plateau on Aoraki - also known as Mount Cook.

Both climbers were found out in the open on Friday morning and it appeared their tent had either been engulfed in snow or had blown away in a storm near the top of the 3,754m mountain, police Inspector Dave Gaskin said.

Mr Nara, who survived the ordeal with frostbite to his face, ears and fingers, was immediately taken to the hospital by helicopter.

The body of Mr Ikenouchi, a mountain guide in Japan with experience in the area, was later recovered by the helicopter team and taken to the rescue base, Mr Gaskin said.

Mr Nara 'is in a remarkable condition, he has frost bite ...... but nothing too severe from what I understand,' he said.

'At that altitude for that length of time it's ... a mystery how one survived at all, actually,' he said.

'It's extreme and a very, very hard area and you don't get second chances. One of them was very lucky and one of them unfortunately wasn't.'

'Horrific' weather had blasted the mountain top on Thursday and overnight,' Mr Gaskin said.

'About three hours after dark they lost contact (with each other). It appears that during the night they got out in the open, which we suspect is because the tent was blown away, and he (Ikenouchi) perished.'

A brief weather clearance on Wednesday allowed rescuers to drop a pack with emergency rations, a cooker, fuel and a radio with instructions in Japanese close to the tent.

No radio contact was made by the pair, and Mr Gaskin said the radio may have been damaged when it landed. High winds at the time prevented a rescue bid.

Mr Gaskin said earlier the situation was similar to one of New Zealand's most famous Mount Cook rescues.

Local climbers Mark Inglis and Phil Doole spent 13 days trapped in bad weather near Mount Cook's summit in 1982. Both men lost their lower legs to frost bite after eventually being rescued by helicopter.

Mount Cook attracts hundreds of climbers each year but can be treacherous - some 150 people have died since it was first conquered in 1894. -- AP