The air-traffic control in Kiruna told the pilot to fly lower over Sweden's tallest mountain, Kebenekaise, moments before the plane crashed.
The daily newspaper Dagens Nyheter reports that the plane was instructed to fly at 2000 metres – 103 metres lower than the southern peak of the mountain.
The five Norwegian citizens on board, who were taking part in an operation by the Norwegian military, all died immediately.
The head of the Norwegian Accident Investigation Authority, Per Egil Rygg, told daily newspaper Verdens Gang that it "wasn't the time to speak about guilt."
"We have only made an analysis which is to be further treated," added Rygg, whose agency has taken part of the report's findings.
Sweden's Accident Investigation Authority emphasized that it has yet to draw any conclusions about what part the instruction to fly lower played in the crash, the news agency TT reported on Friday.
The Hercules plane crashed into Kebenekaise just before 3 pm on 15 March. It was traveling at a speed of 500 kilometres per hour.
Snowy conditions hampered the pilot's navigation of the plane, which lost contact with its base when approaching the mountain, the report said.
The remnants of the plane were buried in an avalanche caused by the crash. Two weeks later, Swedish rescue services removed two tonnes of debris from the site.