Bruno Iksil, the former trader at the centre of JP Morgan’s $6.2bn ‘London Whale’ loss, has turned on the bank's chief executive in a fresh twist to the long-running saga.

Within documents of densely-packed and technical text published on a website Iksil launched last week, the 50-year-old accuses the JP Morgan CEO of helping to sow the seeds of the scandal that engulfed the bank in the spring of 2012.