The National Disability Insurance Scheme integrity chief says nine out of 10 plan managers surveyed showed signs of fraud and the justice system would be overwhelmed if all the scams carried out on the $44 billion program were prosecuted.

In fiery testimony, John Dardo told a Senate committee that internal analysis showed 90 per cent of plan managers that wrangle funding for up to 100 participants (about 900 of 1540 managers in total) portrayed “significant indicators of fraud”.