Keystone oil pipeline portion remains shut over potential leak near Missouri

A portion of TransCanada Corp's Keystone oil pipeline remained shut on Thursday for investigation of a possible leak on its right-of-way near St. Louis, Missouri, a company spokesman said.

TransCanada shut the pipeline down on Wednesday between Steele City, Nebraska and Patoka, Illinois and dispatched crews to assess the situation, spokesman Terry Cunha said in an email. The 590,000 barrels-per-day Keystone pipeline is a critical artery taking Canadian crude from northern Alberta to U.S. refineries. Canadian pipelines are already congested, due to expanding production in recent years, forcing the Alberta provincial government to order production cuts starting last month.

Canadian heavy oil has attracted greater demand due to U.S. sanctions against Venezuela's state oil company. The discount on Canadian heavy crude compared to U.S. light oil widened to $10.15 per barrel on Thursday morning from $9.40 earlier, according to Net Energy Exchange.

TransCanada shares eased 0.2 per cent to C$55.98 in Toronto. An official with the Missouri Department of Natural Resources told Reuters on Wednesday that the release of oil had stopped and it planned to find the leak on Thursday.

A spokesman for the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA) could not be immediately reached. The Missouri Department of Natural Resources did not immediately respond to a request for comment on Thursday.

(With inputs from agencies.)