BP is taking legal action to shift the blame for the Gulf of Mexico oil disaster which devastated the environment and the group's image a year ago, suing rig operator Transocean for damages of $40 billion (24 billion pounds).
The disaster threatened to ruin BP as a business at one point, and the company said it was the victim of bad practice by sub-contractors.
The British oil giant filed suit against Swiss-based Transocean in a New Orleans court on Wednesday, the one-year anniversary of the start of the biggest maritime oil spill in US history.
It also sued oil services giant Halliburton and parts manufacturer Cameron.
Transocean operated the Deepwater Horizon rig which exploded on April 20, 2010, killing 11 workers and causing millions of litres of oil to pour into the Gulf of Mexico.
At one point during the crisis, the future of BP as a group appeared to be at risk from the potential long-term costs of the disaster.
"BP Parties bring this action to hold Transocean accountable for having caused the blowout, explosion, fire, deaths and personal injuries, and subsequent oil spill," the BP lawsuit said.
"But for Transoceans improper conduct, errors, omissions, and violations of maritime law, there would not have been any blowout of the exploratory well," a court filing from BP argued."
The documents added that BP was seeking "at least $40 billion in damages and contribution from Transocean."
The one-year anniversary was the deadline for companies to file claims against each other.
Solemn ceremonies took place in the US on Wednesday to mark the anniversary.
It took 87 days to cap the well, by which time 4.9 million barrels (206 million gallons) of oil had spewed out of the well deep below the surface of the Gulf.
Hundreds of miles of fragile coastal wetlands and beaches were contaminated, a third of the Gulf's rich US waters were closed to fishing, and the economic costs have reached into the tens of billions.
In a separate statement, BP said it had "filed suit against Halliburton in order to hold the company accountable for its critical role in the Deepwater Horizon accident."
Halliburton was responsible for the flawed cement which held the blown-out well in place.
BP said that Halliburton had not provided it with the results of cement tests and company employees "missed critical signals that hydrocarbons were flowing into the wellbore."
And BP said it that was suing Cameron over its design of the blowout preventer on the Macondo well.
"BP has sued Cameron for its faulty design and manufacture of the blowout preventer (BOP), and its negligence in the maintenance and modification of the BOP," said BP.
It was "a critical safety device that failed to prevent the blowout of the Macondo well," added the energy giant.
US investigators said last month that the well might never have blown if the company's engineers had been consulted about a key test that pointed to defective cementing of the well.
The investigation by a presidential commission blamed the disaster on management failures by BP, Halliburton and Transocean.
BP faced protests from angry Louisiana fishermen and disgruntled shareholders a week ago at its first annual general meeting since the devastating oil spill.
BP took a $40.9 billion loss in 2010 related to the spill, including $13.6 billion for the initial response, and hopes to recover a significant portion of the cost from Transocean and Halliburton.
The British oil giant has set up a $20 billion trust fund to cover compensation claims from fishermen and others affected by the spill, but also faces massive fines and penalties from the US government.
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