The United States Court of Appeals for the Ninth Circuit has refused to overturn a ruling that limited TransCanada Corp.'s pre-construction activities on its Keystone XL pipeline, environmental advocacy group the Natural Resources Defense Council said March 15.

The court left in place a ban on right-of-way and other construction activity along the route of the proposed 830,000 barrel-per-day conduit linking Canada's oil sands region with a pipeline hub in Nebraska. TransCanada had argued that the ban could prevent it from starting construction in August, which would mean the start of construction would be pushed back to 2020. The Calgary, Alberta-based company said the delay could cost contractors as much as $2.5 billion.

"Today, the United States Court of Appeals for the Ninth Circuit denied yet another attempt by TransCanada to begin construction on its proposed Keystone XL pipeline," the Natural Resources Defense Council said in a March 15 news release. "The court left in place a ruling by the U.S. District Court for the District of Montana that blocked construction on the controversial tar sands pipeline amid an ongoing legal challenge."