BP's investigation into the causes of the Gulf oil spill has found that two other companies also working on the well should share the blame for the disaster.
The report cited "sequence of failures involving a number of different parties" and said that "a complex and interlinked series of mechanical failures, human judgements, engineering design, operational implementation and team interfaces" lead to billions of barrels of oil leaking into the Gulf of Mexico.
Both Transocean, the company from which BP was leasing the Deepwater Horizon rig, and its cement contractor Halliburton, have criticised the report, saying that BP's own actions raised the risk of an accident.
The 193-page report identified eight different areas in which action could have been taken to minimise risk, including the fact that both BP and Halliburton staff misinterpreted safety test results.
