The US Supreme Court Monday declined to hear a class-action lawsuit by BP shareholders demanding compensation for a sharp fall in share price after the deadly 2010 Gulf of Mexico oil spill.

The justices' refusal to hear the case means a 2015 decision by a lower court which dismissed the suit by the plaintiffs will be upheld.

The shares in question were purchased 2.5 years before the Deepwater Horizon disaster, which killed 11 men and saw millions of barrels of oil flow into Gulf waters, in one of the worst environmental disasters to strike the United States. BP stocks plunged after the incident.

The plaintiffs accused the British oil giant of having deceived shareholders about security procedures it said were in place ahead of the spill.

It took 87 days to cap BP's runaway well -- some 5,000 feet (1,500 meters) below sea level off the coast of Louisiana.

Beaches were blackened in five states and the region's tourism and fishing industries were crippled in a tragedy that riveted the nation.

BP paid a record $20.8 billion to settle government claims for damages stemming from the spill, which has cost the company a total of $55 billion.