An internal BP investigation into the Texas City refinery explosion found John Manzoni, the chief executive of refining, should have done a "much deeper dive" into the true state of the facility after "clear warning signals" from previous accidents.

The confidential report concludes that Mr Manzoni - who until late last year was regarded as being near the top of the list to succeed Lord Browne as BP's chief executive - lacked refining experience and failed to obtain information needed to understand better his complex and important refining asset and the risk of a big accident. The report also reveals tensions between him and Mike Hoffman, then group vice-president for refining and marketing, upon whom he chose to rely for information.