At least 12,000 people have been asked to evacuate oil sand camps close to the Canadian town of Fort McMurray after a fresh wildfire began to shift to the north.

According to the BBC, more than 8,000 people were urged to leave the area on Monday night, in addition to 4,000 people who had already been issued with evacuation orders.

Suncor Energy Inc was among several operators which confirmed on Tuesday that it had been forced to shut down operations as a precautionary measure.

A spokesman said there had been no damage to the company’s assets and that fire defences were in place around the facilities.

Suncor and Syncrude Canada also confirmed they had evacuated workers from the area.

“Suncor has enhanced fire mitigation and protection around all of its facilities,” one Suncor official told AFP.

“When it is safe to do so, we will continue implementing our restart plans,” they added.

Canada’s Alberta province has been battling its worst wildfire in recent memory, with 80,000 people already evacuated from the town of Fort McMurray after the blaze began two weeks ago.

Air pollution in the city remains at dangerous levels, with a recent reading putting it at 38 – far in excess of Canada’s most dangerous level of 10.

The blaze covers roughly 285,000 hectares of land in Alberta and is moving at 140 feet per minute, local officials told AFP.

They said a critical fire barrier to the north of the city had already been overrun by the blaze.

Though firefighters are said to have protected 90% of the town’s buildings from harm, residents are still unable to return to their homes amid fears for their safety.

Rachel Knotley, the Alberta provincial premier, has warned that the toxic air conditions are hampering efforts to get residents back to their homes.

Alberta Health Services has recommended that members of the public who had been previously arranging to return to the area under various requests not return until those conditions improve,” she said.

“This is something that could potentially delay recovery work and a return to the community.”