Warnings in the Intergenerational Report about the growing costs of the National Disability Insurance Scheme have been dismissed by Labor as “rubbery figures” as it signalled it would fight any attempt by the government to rein in the program.

The fifth IGR released on Monday, which is the first since the NDIS was rolled out fully across all states, forecasts an almost 30 per cent cost blowout in the scheme compared to the estimates in the last IGR, which was released in 2015.