Federal Energy Regulatory Commission (FERC) and Commodity Futures Trading Commission (CFTC) had notified BP of the action in November last year, and are currently "investigating certain practices relating to crude oil pipeline nominations procedures on Canadian pipelines," the company said.

"We have responded to CFTC's allegations and challenged their jurisdiction over the alleged conduct," BP said in response to a query from Reuters.

Friction between U.S. commodity regulators and BP is not out of the ordinary. In 2007, BP paid $303 million to settle civil charges that it tried to manipulate propane prices in the United States by cornering the market in February 2004. (http://reut.rs/1LJqZHV)

The company is also fighting a case with the FERC over allegations of natural gas market manipulation in Texas. (http://reut.rs/1yDnv0u)

(Reporting by Ankush Sharma in Bengaluru; Editing by Diane Craft)