CALGARY -- The CEO of Suncor Energy Inc. says attempts by Michigan state politicians to retire the Line 5 pipeline running through a Great Lakes channel is a “huge potential threat” for consumers in Michigan as well as Ontario and Quebec.

Speaking during the TD Securities energy conference, Mark Little says his company's refineries in Sarnia, Ont., and Montreal are operating normally despite the line's recent shutdown and partial restoration.

But he adds that the use of rail transportation and ships in place of the pipeline drives up costs and will have an affect on consumers.

Line 5 owner Enbridge Inc. shut down both legs of the pipeline last month after noticing a disturbance to an anchor support on its underwater east leg in the Straits of Mackinac.

The west leg was restarted, then ordered shut down by a judge at the request of state Attorney General Dana Nessel, who has also asked for a preliminary injunction that could keep Line 5 closed indefinitely.

Last week, the judge allowed the west leg to reopen but the other leg remains closed until more testing is completed.