Adventurer Hyoichi Kono has not contacted his support group since Thursday in his six-year trek from the North Pole to his native Ehime Prefecture, supporters said Monday.
The secretariat of the support group in Matsuyama, Ehime Prefecture, quoted its group members at Kono's base camp in Resolute, Canada, as saying no details from the Canadian Air Force have been available.
A private plane dispatched by the group spotted Kono's sled and some belongings, but the whereabouts of the 43-year-old adventurer remain unknown.
At the request of the members, the Canadian Air Force later sent a plane to the area where the belongings were found.
Kono, who kept in daily contact with the secretariat by radio, last did so around 11 a.m. Thursday from Eureka near the Arctic Sea, the supporters said.