NEW ORLEANS — BP's long-awaited internal report on what it believes went wrong when a rig exploded and started the massive Gulf oil spill never mentions the words blame, regret, apology, mistake or pollution. The word fault shows up 20 times, but only once in the same sentence as the company's name.

BP took some of the blame, acknowledging among other things that it misinterpreted a key pressure test of the well that blew out and eventually spewed 206 million gallons of oil into the Gulf. But in a possible preview of its legal strategy, it also pointed the finger — and plenty — at its partners on the doomed rig.

The highly technical, 193-page report released Wednesday attributes the worst offshore oil spill in U.S. history and the deadly rig explosion that set it off to a complex chain of failures both human and mechanical. Some of those problems have been made public over the past 4½ months, such as the failure of the blowout preventer to clamp the well shut.

The report is far from the definitive ruling on the cause of the catastrophe. For one thing, government investigators have not yet begun to fully analyze the blowout preventer, which was raised from the bottom of the sea over Labor Day weekend.

But it does provide an early look at the company's probable legal strategy — spreading the blame among itself, rig owner Transocean, and cement contractor Halliburton — as it deals with hundreds of lawsuits, billions of dollars in claims and possible criminal charges in the coming months and years.

For Billy Nungesser, president of oil-soaked Plaquemines Parish, the report doesn't change the fact that in his mind the time that has passed since the disaster hasn't made offshore drilling safer.

"If they believe painting the rigs yellow would make them safer, stop delaying, give us a bucket of paint and let us get started," Nungesser said of those in power.

Critics of BP called the report self-serving.

"This report is not BP's mea culpa," said Rep. Edward J. Markey, D-Mass., a member of a congressional panel investigating the spill. "Of their own eight key findings, they only explicitly take responsibility for half of one. BP is happy to slice up blame as long as they get the smallest piece."

The disaster began when the Deepwater Horizon exploded off the coast of Louisiana on April 20, killing 11 workers. BP's well spewed oil into the Gulf for three months before a temporary cap stopped it in mid-July.

Members of Congress, industry experts and workers who survived the blast have accused BP's engineers of cutting corners to save time and money on a project that was 43 days and more than $20 million behind schedule at the time of the blast.

Nearly 24 hours before the explosion, Halliburton was using cement to seal the gap between the well casing and the hole drilled in the seafloor. It was also cementing the bottom of the well shut until the day BP was ready to begin extracting oil and gas from it.

In its report, BP said that it was a bad cementing job that contributed to the blowout and that the design of the well was probably not to blame. It also said "more thorough review and testing by Halliburton" and "stronger quality assurance" by BP's well team might have identified weaknesses in the plan for cementing.

"BP blaming others for the Gulf oil disaster is like Bernie Madoff blaming his accountant," said Robert Gordon, an attorney for fishermen, hotels and restaurants affected by the spill.

The report acknowledged, as investigators have previously suggested, that BP's engineers and employees of Transocean misinterpreted a pressure test of the well's integrity before the explosion.

They also blamed employees on the rig from both companies for failing to respond to other warning signs that the well was in danger of blowing out.

"The team did not identify any single action or inaction that caused this accident," the investigators said. "Rather, a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces came together to allow the initiation and escalation of the accident."

Mark Bly, who as BP's safety chief led the internal investigation, said the report was a reconstruction of what happened on the rig based on the company's data and interviews with mostly BP employees and was not meant to focus on assigning blame.

Transocean blasted the report as a self-serving attempt to conceal what it called the real cause of the explosion — "BP's fatally flawed well design."

Halliburton said it found a number of omissions and inaccuracies in the report and is confident the work it completed on the well met BP's specifications. "Contractors do not specify well design or make decisions regarding testing procedures as that responsibility lies with the well owner," the company said.

White House press secretary Robert Gibbs noted "there is an active investigation into what went wrong" and said the administration's job is to find out what happened and hold those responsible accountable. Federal prosecutors are among those investigating.

In Wednesday trading in New York, BP stock rose $1.18, or 3.2 percent, to close at $38.37.

Investigators know the explosion was triggered by a bubble of methane gas that shot up the drill column and ignited. But they don't know exactly how and why the gas escaped. And they don't know for certain why the blowout preventer didn't work.

But in its report, BP said the blowout preventer didn't do its job because it was damaged in the explosion and because it had a bad valve and weak batteries. Transocean, which was responsible for maintaining the blowout preventer, has insisted the batteries were in working order.

(AP Writers Dina Cappiello, Harry R. Weber and Michael Kunzelman authored this report. Cappiello reported from Washington. Associated Press Writers Curt Anderson in Miami, Chris Kahn in New York and Seth Borenstein in Washington contributed to this report.)