A key federal report has leveled much of the blame on BP for last year's Gulf of Mexico oil spill, the worst offshore spill in U.S. history.

The U.S. Coast Guard and Bureau of Ocean Energy Management, Regulation and Enforcement report , released Wednesday, says the disaster is the result of poor risk management, a faulty cement job, and a series of misinformed decisions by the rig's crew.

The report says the British oil company, BP, was “ultimately responsible” for the operations on the Macondo well and for the safety of its workers. But the report also points a finger at Transocean, owner of the oil rig; Halliburton, the company responsible for cementing the well; and Cameron, a company responsible for the blowout preventer on the oil rig.

BP responded Wednesday saying the report was “consistent” with other official investigations that cited multiple causes and multiple parties involvement. It said it has since taken steps to improve safety and risk management, and hopes its partners take responsibility for their roles in the disaster.

Earlier reports placed similar blame. The presidential commission report, released earlier this year, said the deadly explosion resulted from BP and it's partners cutting costs and taking shortcuts. It also specifically singled out a flawed design of the cement used to seal the well.

The Deepwater Horizon oil rig explosion in April 2010 killed 11 people and set off an 85-day underwater leak that spewed nearly 5 million barrels of oil into the Gulf of Mexico.

Lawsuits, investigations, and changes in industry regulation have resulted since the disaster. The new report is expected to lead to further legal ramifications for BP and its partners.