The state's highest court, upholding the views of lower courts, ruled BP was covered by Transocean's insurance for pollution on the water's surface, but not under it.

BP operated the well, while Transocean owned and operated the Deepwater Horizon rig that burned and sank when Macondo erupted, killing 11 men.

BP is awaiting a separate ruling from a New Orleans federal judge, expected some time this year, over its fines under the U.S. Clean Water Act. Those would exceed more than $42 billion the oil major has set aside for cleanup, compensation and other fines related to the spill.

Shares of BP were 2.2 percent higher on Friday.

(Reporting by Terry Wade; Editing by Chris Reese)