New California fuel rule may violate NAFTA: lawyer

"Canada's overall energy integration with the United States and our common goal of reducing green house gas emissions makes it all the more important that our individual efforts to address climate change do not lead to the creation of unnecessary barriers," the statement said.

"We are continuing to examine the potential consequences for trade of California's LCFS regulations."

While little or no oil sands crude is currently exported to California, the Alberta government said it considers the provision a threat because the state is a potential market. Also, other U.S. states are considering similar regulations.

"Does it have a possibility of a negative effect on Alberta's bitumen future? I would suggest I'd be very naive if I thought anything other than 'yes' is the proper answer to that," Alberta Energy Minister Mel Knight said Friday in Houston.

(Additional reporting by Bruce Nichols and Jeffrey Hodgson; Editing by Alex Richardson)