Officials say massive wildfires in Saskatchewan continue to burn out of control, with one blaze now more than five times the size of Saskatoon, the province's largest city.

Steve Roberts, an official with the province's Wildfire Management Branch, said Friday that about 1,300 people are fighting the fires, including soldiers and crews from across Canada.

Wildfires also continue to burn in British Columbia and Alberta, triggering air advisories across central and western Canada, as well as parts of the western U.S.

Kim Weir, a Parks Canada spokeswoman, says a wildfire burning in Jasper National Park has grown substantially, forcing campers and other visitors out of the area.

The popular park remains open, but with a ban on campfires.

Thousands across western Canada have been evacuated.