WASHINGTON The U.S. Supreme Court on Monday declined a request from shareholders seeking to revive their class action lawsuit against BP (BP.L) claiming the British oil company misrepresented its safety procedures prior to the 2010 Gulf of Mexico oil spill.The court left in place a September 2015 ruling by the New Orleans-based 5th U.S. Circuit Court of Appeals that refused to certify the lawsuit filed by investors who bought shares in the 2-1/2 years before the spill. BP's share price plummeted after the disaster that has cost the company more than $55 billion.BP said in court papers the lawsuit should not be allowed to proceed because the plaintiffs were improperly seeking damages for the entire decline in stock price as a result of the spill. The appeals court said some of the investors might have bought the stock even knowing the risk, and these investors may still sue BP individually. In the same ruling, the appeals court allowed a lawsuit by investors who bought shares after the spill to move forward.The April 20, 2010, Deepwater Horizon drilling rig explosion and Macondo oil well rupture killed 11 workers and caused the largest offshore environmental disaster in U.S. history, polluting large parts of the Gulf, killing marine wildlife and harming businesses. It took 87 days to plug the leak on the ocean floor. In total, BP has incurred about $55 billion in losses as a result of the spill, including $18.7 billion to settle federal, state and local claims. The case is Ludlow v. BP, U.S. Supreme Court, No. 15-952. (Reporting by Lawrence Hurley; Additional reporting by Jonathan Stempel; Editing by Will Dunham)