Oil prices jumped on Monday as a huge wildfire in Canada's oil sand region knocked out over a million barrels in daily production capacity, contributing to a significant tightening of markets over the past weeks.
The lost capacity is equivalent to well over a third of the country's typical daily production.
US crude futures were trading at $45.51 per barrel at 0214 GMT, up 85 cents, or 1.9 percent, from their last settlement.
Brent crude was up 62 cents, or 1.4 percent, at $45.99 a barrel.
While supplies tighten, demand, especially in Asia, is holding firm.
China's monthly imports of crude oil rose 7.6 percent in April from a year ago to 32.58 million tones, customs data showed, lifted by strong demand from domestic private refiners.