Former treasurer Wayne Swan has warned the National Disability Insurance Scheme is “unsustainable” and “running out of control”, putting the rapidly growing social program at risk of losing community support.

The independent budget watchdog expects the $42 billion program to overtake the age pension as the most expensive area of government spending within a decade, even if Labor successfully cuts the scheme’s annual growth rate to 8 per cent from 20 per cent, The Australian Financial Review revealed on Friday.