Calgary, June 24:Power cuts in the Canadian oil capital of Calgary could last for weeks or even months, city authorities said on Sunday, after record-breaking floods swept across southern Alberta, killing three people and forcing more than 100,000 to flee their homes.

Some Calgary residents were able to return to sodden homes as rivers dropped and some evacuation orders were lifted. But Bruce Burrell, director of the Calgary Emergency Management Agency, said power restoration in the city centre, where many of Canada's oil companies have their headquarters, could take days, weeks or even months. Many oil companies were making plans for employees to work from home.

"This is an evolving situation and because of the volatility of electricity and water and the infrastructure that was damaged we have got a lot of issues with restoring power to different parts of the city of Calgary," Alderman John Mar told CBC radio. "We are facing an absolutely gargantuan task."

Heavy rains were blamed for the spilling of 750 barrels of synthetic oil from a pipeline about 70km (43 miles) south of Fort McMurray in northern Alberta early on Saturday.