Hundreds of Canadian oil workers have been ordered to evacuate camps near the fire-hit town of Fort McMurray as a resurgent wildfire heads towards them.

Alberta State Premier Rachel Notley said up to 600 workers were being sent to oil sands installations further north.

About 4,000 more workers are on standby to evacuate if necessary.

More than 80,000 people fled Fort McMurray two weeks ago when a wildfire swept through the town.

The vast fire moved away but in recent days it has started to threaten the area again.

On Monday, a wildfire was travelling at 30-40 metres per minute north of Fort McMurray, a statement from the municipality of Wood Buffalo said.

All northbound traffic had been stopped at the city, it added.

Fort McMurray wildfires - in-depth

Hundreds of workers in the camps closest to the flames have been ordered to move away while thousands more were put on standby.

There are 12 oil sands camps in the area.

Thick smoke and ash over a wide area are said to be hampering the fire-fighting operation and hot-dry winds have been fanning the flames.

Fire crews were also trying to control a blaze south-east of Fort McMurray that is threatening an oil installation.

Canadian Finance Minister Bill Morneau told CBC News that the cost of the disaster was still being evaluated.

"We're obviously going to stand shoulder to shoulder with the people in Fort McMurray and rebuild the city," he said.

More than 2,400 buildings have been destroyed in Fort McMurray and thousands of evacuated residents continue to live in temporary shelters.

Officials say they hope a plan will be ready within two weeks to return residents to their homes.

The wildfire still covers about 2,410 sq km (930 sq miles) and is expected to burn for a few more weeks.