CALGARY -- BP says it has restarted operations at a major unit of a U.S. refinery that processes oilsands crude from Alberta after a malfunction earlier this month.

The forced shutdown of the 240,000-barrel-a-day crude distillation unit in Whiting, Ind., on Aug. 8 caused gasoline prices to spike across Western Canada.

The closure also led to a wider discount on Canadian heavy crude, which dropped to more than US$20 below the North American benchmark price.

BP says the Whiting restart is increasing the refinery's fuel production as it ramps up output over time.

The resumption of operations comes a day after oil closed at a fresh six-year low of US$38.24 a barrel for the West Texas Intermediate benchmark crude after dropping $2.21 on the day.

Analysts say many oilsands operations are producing at a loss at these prices.