US regulators failed to catch Bernard Madoff’s huge fraud in 2006 because they asked the wrong questions and did not perform “accounting 101”, the financier told the authorities earlier this year, according to documents released on Friday.

In an interview in June – days before he was sentenced to 150 years in prison for crafting the biggest “Ponzi” scheme in history – Mr Madoff told the Securities and Exchange Commission it was “amazing” he had not been caught earlier.