Keystone pipeline shut after oil release

"The system remains shut down as our crews actively respond and work to contain and recover the oil," the release said.

The company was not immediately available to comment on the volume of the release.

Keystone ships Canadian crude from Alberta to the US midwest and on to the Gulf Coast, and is a key part of Canada's oil export network.

On November 15, the company announced it would curtail volumes on the pipeline due to some severe weather-related incidents without specifying the size or duration of the curbs.