BP is one of nine defendants listed by the US Attorney General's office, and could be liable "without limit" if found guilty. Any figure would be in addition to the $20bn BP has already agreed to pay into a fund to compensate people on the Gulf coast.
The well drilled by Deepwater Horizon leaked oil for three months following the explosion, which killed 11 people.
Eric Holder, US attorney general, said: "We intend to prove that these defendants are responsible for government removal costs, economic losses, and environmental damages without limitation.
"Even though the spill has been contained, the department’s focus on investigating this disaster and preventing future devastation has not wavered. Both our civil and criminal investigations continue, and our work to ensure that the American taxpayers are not forced to bear the costs of restoring the gulf area and its economy is moving forward."
The suit claims that BP failed to:
- Take necessary precautions to keep the Macondo Well under control in the period leading up to the 20 April explosion
- Use the best available and safest drilling technology to monitor the well’s conditions
- Maintain continuous surveillance
- Use and maintain equipment and material that were available and necessary to ensure the safety and protection of personnel, equipment, natural resources, and the environment
The suit maintains that BP will be liable for unlimited damages under the Oil Pollution Act, and civil penalties will be sought under the Clean Water Act for discharging oil into the Gulf of Mexico.
Oil from the leaking well spread over a large portion of the Louisiana coastline. BP claims to have spent some $39.9bn (£24.9bn) on clean-up and other costs since the disaster, and put aside $20bn to pay "all legitimate claims" from the spill.
BP has issued a robust defence, claiming the suit was: "...solely a statement of the government’s allegations and does not in any manner constitute any finding of liability or any judicial finding that the allegations have merit."
BP's statement continued: "BP will answer the government’s allegations in a timely manner and will continue to cooperate with all government investigations and inquiries.
"Alone among the parties, BP has stepped up to pay for the clean-up of the oil, setting aside $20bn to pay all legitimate claims. We took these steps before any legal determination of responsibility and will continue to fulfil our commitments in the Gulf as the legal process unfolds."
The fall-out from the Deepwater Horizon incident has been highly damaging for BP, costing chief executive Tony Hayward his job.
BP suspended its marketing activity while the spill continued in the Gulf, but then spending tripled in an attempt to counter the ongoing bad publicity surrounding the spill.
Rival Shell has been highly critical of the "Beyond Petroleum" slogan BP used prior to the spill, and BP's top marketer Luc Bardin has admitted that the brand is "tarnished" and has a massive task ahead to rebuild the brand.
The companies to be included in the suit are:
- BP Exploration and Production Inc
- Anadarko Exploration & Production LP and Anadarko Petroleum Corporation (known collectively as Anadarko Defendants)
- MOEX Offshore 2007 LLC
- Triton Asset Leasing GMBH
- Transocean Holdings LLC, Transocean Offshore Deepwater Drilling Inc, and Transocean Deepwater Inc (known collectively as Transocean Defendants)
- Transocean’s insurer, QBE Underwriting Ltd/Lloyd’s Syndicate 1036, which can be held liable only up to the amount of insurance policy coverage under the Oil Pollution Act and is not being sued under the Clean Water Act