The government of Canada's Alberta province said Sunday the massive wildfire would, by the end of the day, cover more than 200,000 hectares (495,000 acres) - an area equivalent to Britain's Greater London. The fire was continuing to grow.

High temperatures, dry conditions and strong winds were helping to fan the flames southeast of the evacuated town of Fort McMurray, close to the border of the next province, Saskatchewan. But fire officials were hopeful the fire would move further away from heavily populated areas.

Forecasters said a small amount of rain was forecast for the area but that it would not be enough to put out the fire. They added that a heavy downpour would be needed for several days to help dowse the inferno.

The Royal Canadian Mounted Police has confirmed that a two-day evacuation of tens of thousands of residents from Fort McMurray was now complete. Scores of families who initially fled north from the town were forced to return through the burning town, after the blaze cut off their escape route. Police then helped drivers head south to safety.

Thousands of evacuees are camped out in nearby towns but stand little chance of returning soon, even if their homes are intact.

Provincial officials said displaced people would be better off driving to cities such as Calgary, 655 km (410 miles) to the south, where health and social services were better.

No deaths or injuries have been reported since the fire started last Sunday.

Airlift away from oil sands

Officials said about 12,000 evacuees have also been airlifted away over the past two days, and about 7,000 have left in highway convoys escorted by police. The wildfire is expected to reach the edges of the Suncor oil sands facility, about 15 miles (25 kilometers) north of Fort McMurray, they added.

Oil sands are either loose sands or partially consolidated sandstone containing a naturally occurring mixture of sand, clay, and water, saturated with petroleum known as bitumen.

The blaze and mass evacuation has forced a quarter or more of Canada's oil output offline and was predicted to impact an economy already hurt by the fall in the price of oil. The Alberta oil sands have the third-largest reserves of oil in the world behind Saudi Arabia and Venezuela.

More than 500 firefighters were in and around Fort McMurray, along with 15 helicopters, 14 air tankers and 88 other pieces of equipment, officials said.

One exhausted fireman told Canada's CBC television that members of his team were working up to 40 hours at a stretch without sleep.

mm/jm (AFP, AP, Reuters)