Two large wildfires that started this summer are still burning and likely will continue to burn under cover of snow and ice through this coming winter, officials in the N.W.T. said Tuesday.

The fires, both in the Dehcho region of the Northwest Territories, are burning underground, burning up roots and other flammable material.

One fire near the Jean Marie River west of Yellowknife covers an area about the size of the city of Edmonton. The other, a smaller one roughly the same size as Red Deer, is burning further north, near Wrigley.

"They're relatively calm compared to this summer," says Richard Olsen, a manager of fire operations with the territorial government in Fort Smith. "There are still some areas that are smoking away, those conditions are pretty dry in those areas so those fires will continue to burn well into winter."

Instead of helping to extinguish the flames, Olsen says snow and ice is likely to provide ideal cover for the fire to smoulder away through the winter.

"The ground is like a sponge," Olsen says "and when that sponge dries up it's available to burn."

Any amount of oxygen will help the fires grow, Olsen says.