BP has said it is willing and able to pay them; but investors appear terrified that the list of claimants could extend far beyond that.

Rather than waiting for messy court battles, Singapore has taken the novel step of asking firms to reimburse "vulnerable customers", meaning those who are old or illiterate or who lost a lot.

The company won a dismissal of the lawsuit last year but had warned investors that it could be on the hook for "hundreds of millions" of dollars if it eventually loses the case.