The head of the Norwegian Armed Forces, Harald Sunde, told Norwegian state broadcaster NRK that Swedish rescue teams found pieces of wreckage smelling of aircraft fuel.
"Yes, the Swedish rescue crews have declared the area an accident site based on these finds," he said.
"We've received information from a Swedish rescue team that it smells like paraffin near the wreckage. We also have information from our own team that they can see the wreckage."
Swedish military sources also confirmed for the TT news agency that wreckage of the missing plane had been found near Mount Kebnekaise, Sweden's highest peak.
Swedish rescue workers leading the search operation in the far north of Sweden said the airplane itself had not yet been found.
“We have now managed to confirm that a Swedish unit at Storglaciären (‘The Grand Glacier') has found a number of objects,” said the Swedish rescue services.
“They have found a padded object and a Velcro strip, all drenched in paraffin. Photographs have been taken and sent to the Norwegian army.”
Earlier on Friday afternoon, a Norwegian Orion search plane observed an unidentifiable orange-coloured object on a hillside by Mount Kebnekaise.
“The pilots who spotted it were lucky; there must have been a window in the cloud coverage. We sent a Swedish military helicopter up there just after but he saw nothing,” Peter Lindquist of the Swedish sea and air rescue services told the TT news agency.
The unidentified object was spotted on a hillside near Kebnekaise, Sweden's highest peak. There has reportedly been an avalanche in the area as well.
The Norwegian Orion plane will continue to circle the area while two Danish helicopters are joining the search. On the ground, the emergency services are working on getting rescuers to the area.
Problematic weather conditions, with strong winds and blizzards, are hampering the rescue mission for helicopters and ground-based personnel.
A Hawkeye aircraft is en route from Britain to help with the search.
”It is a surveillance and radar aircraft and we will link our communications through that. It will coordinate our helicopters,” said Tobias Nicander at the sea and air rescue services to TT.
According to Per-Olov Wikberg, coordinator for the Mountain Safety Council of Sweden (Fjällsäkerhetsrådet), it is difficult to rate the chances of survival in the type of harsh terrain where the plane is thought to have crashed.
“If you are uninjured, dressed correctly and have access to water, you might manage ten days,” he told TT.
”This is the most alpine terrain we have in Sweden. It is the very worst place to end up in this weather,” he said.
The missing aircraft is a C-130 J "Super" Hercules transport plane manufactured by Lockheed Martin in the United States.
The plane is one of four C-130 Js ordered by the Norwegian air force in 2007, the first of which was delivered in November 2008.