The largest water bomber in the world is flying to Alberta from British Columbia to help fight wildfires in the oilsands region.

Alberta Sustainable Resources says the Martin Mars is to begin dropping huge loads of water Saturday on the Richardson backcountry fires.

The fires have been burning north of Fort McMurray for about three weeks in a 3,600 square kilometre area.

Oilsands companies in the region continue to reduce staff in northeast Alberta because of the fires.

The four-engine Martin Mars will be based on Gregoire Lake.

The Second World War-era aircraft can scoop up 27,000 litres of water for each flight.