Top management at Shell believes the company has a second-rate safety record in the North Sea and has failed to tackle the problem because parts of the organisation are in denial.
The revelation in an email to staff from Jeroen van der Veer, Shell's chief executive, comes ahead of today's half-year financial presentation, when he will be under pressure to explain what is going wrong.
The difficulties were highlighted last month by the Guardian in an interview with one of Shell's own safety consultants, Bill Campbell. He said little had been done to tackle poor safety procedures on many platforms first identified in 1999. Then an accident inquiry report published this month into two deaths on the Brent Bravo platform in 2003 seriously criticised the company.
In the message to staff sent 10 days ago, Mr van der Veer is blunt about the company's failings. "Our safety performance has reached a plateau - and remains below best of class in our industry. Our statistics show it. We know it. Are we not trying hard enough, focusing hard enough or haven't we accepted that we have a problem? I think it's a mixture. All these problems are probably part and parcel of the safety problem."
The Shell boss says safety should be foremost in everyone's minds. "I ask you to ask yourself - are you aware of what more you can do, and when you can and must intervene? And are you clear on how to do this before something goes wrong in operations around you? Have you been learning from past mistakes?"
Mr Van der Veer points out that a $1bn improvement programme is under way in the North Sea but he accepts that "the debate in the media is likely to continue about whether we have done enough to ensure technical integrity, safety standards and safety behaviour in that area of operations". He insists his company has done all it can to act on recommendations made by Mr Campbell in 1999. "We genuinely believed we did," says the chief executive, who will unveil second-quarter profits of around $6.1bn (Â£3.3bn) today.
Mr Van der Veer says improved safety depends on "willpower, behaviour and taking action" but he adds it will take "years" to convince critics that procedures have improved.