Four BP executives should be sacked for failing to prevent a fatal blast at the oil giant's Texas City refinery in 2005, an internal report has said.
BP has taken extensive steps to improve safety since the incident
The report, released by court order, also found that a fifth manager ignored "serious warning signals" at the site.
BP is being investigated by the US Chemical Safety Board (CSB) and US Justice Department over the explosion which killed 15 people an injured 180.
BP said it had read and reviewed the report but would not comment on it.
Among the managers singled out by the report was Mike Hoffman, group vice- president for refining and marketing.
The four "failed to perform their management accountabilities in significant ways", it said.
One executive has since left the company, while the other three executives have since been moved to other parts of the group.
BP was also heavily criticised for failing to provide clear lines of responsibility.
It added that managers routinely ignored standard procedures, failed to act in the best interests of the firm and management systems failed to perform at the highest level.
The report was released by lawyers representing some of the victims of the March 2005 disaster.
The revelations come just two days after the oil giant's chief executive, Lord Browne, resigned after a UK court lifted an injunction against a newspaper preventing it from printing revelations about his private life.
US investigators have already rapped the company over the blast.
The CSB blamed lax safety culture at the firm as well as cost-cutting, bad management culture and worker fatigue.
The aftermath of the Texas City blast is not the only safety investigation that BP faces in the US.
In addition, the firm had to close part of its Prudhoe Bay oil field in Alaska earlier this year, after leaks were discovered in one of its pipes.