Police are following up reported sightings of an American tramper outside Nelson Lakes National Park where they have been searching since last week.
The last confirmed sighting of Edward Reynolds, 39, was at a park hut seven weeks ago.
A ground search of nearby mountainous terrain has been curtailed by poor weather.
However, search and rescue spokesman Sherp Tucker says one or two reported sightings of Mr Reynolds elsewhere in the South Island are also being investigated.
He says the quality of that information is uncertain.