The owner of the rig that exploded last year in the Gulf of Mexico has blamed oil company BP for the disaster, which killed 11 people and triggered a massive oil spill.

In a report released Wednesday, Transocean said the disaster was related to a series of well design, construction and temporary abandonment decisions that compromised the well's integrity and made it more likely to fail.

Transocean said BP made many of those decisions in the two weeks before the explosion.

Its report also said BP failed to properly assess and communicate the risks around the well.

The accusation marks the latest chapter in the debate about who should pay the costs from the maritime disaster.

In April, BP announced plans to sue Transocean and another company, Cameron International, asking for $40 billion from the companies to pay their share of the liabilities.

BP said the rig's blowout preventer, made by Cameron International, was faulty and helped cause the disaster. It also said Transocean missed key signs that hydrocarbons were building up in the drilling equipment, and failed to take appropriate action.

The Deepwater Horizon explosion in April 2010 touched off an 85-day underwater leak that spewed nearly 5 million barrels of oil into the Gulf of Mexico. It was the worst offshore oil spill in U.S. history.

The United States said late last year it is suing BP and eight other companies for their roles in the spill.