Officials in Canada issued mandatory evacuation orders on Monday for 500 to 600 workers at several small camps close to the oil sands hub of Fort McMurray in the province of Alberta.

As a precaution, another 4,000 employees at other camps nearby were also asked to leave. Flames lapped at the forest around 15 to 20 kilometers (9 to 13 miles) from several oil sites.

The evacuations were a "precautionary measure" and "the facilities are not at risk," said Sneh Seetal, a spokesman for Suncor Energy, which owns some of the camps. "However, we felt it was important to take these steps in the interest of putting people first."

The fires have threatened a crude oil tank farm south of Fort McMurray, which local officials have described as critical infrastructure. Firefighters said they were considering whether to spray down the facilities.

Roughly a million barrels per day of oil sands crude production was shut off as a precaution when the fire spread out of control around two weeks ago. Much of that production remains offline.

According to officials from the Wood Buffalo rural municipality, the main wildfires were moving at up to 40 meters (44 yards) per minute and is expected to burn six kilometers (3.7 miles) in two hours.

Local officials said firefighting efforts would be further hampered over the next couple of days with hot, dry conditions and lightning fires expected. Thick smoke is also posing a hazard to air quality, they added.

The massive blaze remains out of control as it moves eastward, about 12 kilometers from the Alberta-Saskatchewan province.

Firefighters have managed to protect much of Fort McMurray, which was evacuated two weeks ago when the wildfire first erupted.

The entire population of the city - about 90,000 people - was forced to flee as the blaze ravaged several neighborhoods. Evacuated residents have been warned it may be several days or weeks before they are allowed to return to their homes, partly because of thousands of hotspots around the community.

Elsewhere in the province, new forest fires broke out over the weekend, leaving a total of 15 separate blazes, three of which are out of control, officials added.

mm/cmk (AFP, AP, Reuters)