Former treasurer Wayne Swan has launched a scathing attack on the head of Tony Abbott's Commission of Audit, accusing business leader Tony Shepherd of being an ''an unthinking mouthpiece for the Liberal Party'' with ''zero understanding'' of the importance of social reforms such as the National Disability Insurance Scheme.

The comments are Mr Swan's most significant political intervention since Labor lost office last September.

Former treasurer Wayne Swan: "I’ll always be proud of what Labor did in government to steer our country through the most tumultuous economic period in living memory." Credit:Dominic Lorrimer

Mr Shepherd, the outgoing president of the Business Council of Australia, said in his farewell speech on Thursday night that he was looking forward to the release of the commission of audit report because ''the former government should be held to account for the budgetary decisions they made''.

Mr Shepherd said Labor had locked long-term commitments into future budget cycles that "they must have known Australia couldn't afford on any reasonable projections".