Police said the truck caught fire while traveling through the Brattli Tunnel in Tysfjord Jan. 17 and the cargo, caramelized brown goat cheese, kept the fire burning for five days, Norwegian broadcaster NRK reported Wednesday.
No injuries were reported from the blaze.
Officer Viggo Berg said the high concentration of fat and sugar in the cheese can cause it to burn "almost like petrol if it gets hot enough."
Geologist Viggo Aronsen said the tunnel is likely to remain closed for several weeks.
"We can't go in until it's safe," Aronsen said.
Kjell Bjoern Vinje of the Norwegian Public Roads Administration said he was unaware of any previous incidents involving cheese catching fire on a road, the BBC reported.
"I didn't know that brown cheese burns so well," he said.