The prospect of a prolonged clean-up from a leak along a large oil pipeline sent US crude prices higher on Wednesday, as traders braced for lower supplies from Canada. The Keystone pipeline, which runs south from the Alberta oil sands to American refineries, spilled about 5,000 barrels in South Dakota last week, owner TransCanada said. The incident took place four days before TransCanada won a critical permit to build another pipeline south from the oil sands called Keystone XL. The line remained closed on Wednesday as company staff and federal pipeline safety officials worked at the spill site. A manager with the South Dakota Department of Environment and Natural Resources told Reuters that the clean-up will take several weeks, suggesting that flows on the 590,000 barrels-per-day artery will continue to be curtailed. “With no timeline for restart, expect roughly 4m barrels per week of Canadian imports to be backed out,” TAC Energy, a fuel wholesaler, said in a note to customers. The news pushed the price of West Texas Intermediate, the US oil benchmark, to a 28-month high of $58.09 a barrel, up 2.2 per cent on the day. The price of WTI for prompt delivery also rose in comparison to contracts for future delivery, suggesting traders were scrambling to obtain immediate supplies.