TORONTO, May 29 (Reuters) - Suncor Energy Inc is resuming operations after its sites in Canada's energy heartland of Alberta stopped production because of a wildfire, the company said on Sunday.

It said in a statement the restart began with resuming "initial production" in its Firebag site last week and that a start-up in its base plant and MacKay River site had begun, with initial production expected to be up by the end of the week.

The exact production volume was not immediately clear.

Suncor also said that Syncrude, majority-owned by the company, was planning its own return to operations.

The company added it would move 3,500 more people in the coming week to its facilities north of Fort McMurray, Alberta, from elsewhere in Canada to support its return to operations.

The wildfire in and around Fort McMurray let to a shutdown that has cut Canadian oil output by a million barrels a day. The city itself still sits largely empty after its entire population of nearly 90,000 was evacuated when the fire hit earlier this month. The inferno has charred more than 500,000 hectares (1,930 square miles) across northern Alberta.

(Reporting by Ethan Lou in Toronto; Editing by Peter Cooney)