A war of words broke out today between BP and Transocean after a long-awaited report by the oil company into the worst crude spill in US history placed much of the blame on the US rig operator.

The investigation team working for BP avoided making many references by name to Transocean in its summary but claimed that "multiple companies" and mistakes were at the heart of the Deepwater Horizon blowout.

It went on to list eight key findings related to the causes of the accident and at least five of them appeared to come under the area of responsibility that could be attributed to Transocean rather than BP.