Jamie Dimon, chief executive of JPMorgan Chase, on Thursday hit out at strict rules on US credit cards, saying they would cost the bank’s lossmaking card unit up to $700m next year.

His comments came after JPMorgan underlined its status as one of the winners from the crisis, beating expectations with second-quarter earnings of $2.7bn, up 36 per cent from a year ago, thanks to strong investment banking revenues.