In its latest report the Public Accounts Committee (PAC) says the credibility of the Treasury's Whole of Government Accounts (WGA) continues to be undermined by the omission of a number of public sector bodies, including Network Rail and the government-owned banks, in defiance of normal accounting rules.

While describing the WGA for 2011-12, published in July 2013, as 'the best yet', PAC stated that 'there is room for improvement in the document itself and how it is used'. The committee said the usefulness of the WGA is limited by the length of time it takes to produce the document and by poor quality data from some of the bodies.

PAC commented on the fact that the figure for government debt and deficit highlighted in the WGA (£185bn) differs from the one reported in the ONS's National Accounts used by the Chancellor (£90bn) and suggests users might find this hard to reconcile.

PAC chair Margaret Hodge said: 'Also, by changing definitions in its commentary published alongside the WGA, the Treasury makes it difficult to track changes over time. So, for instance, the Treasury's introduction in the commentary of a new concept of so-called "direct" expenditure leaves out key costs such as the interest paid on the National Debt.'

In addition, Hodge expressed concern that the accounts have again been qualified over the completeness, timeliness and accuracy of the information supplied for schools and academies, pointing out that this issue is likely to become more significant as the number of academies is set to rise rapidly.

In its recommendations, the PC says the Treasury should make the differences between the National Accounts and the WGA clearer and provide a more transparent and complete picture in presenting directly controlled expenditure. It wants the department to review its decision to omit publically owned and controlled bodies like academies.

It calls on the Treasury to set out how it will ensure that the government makes much better use of the WGA to inform decisions, particularly in areas that involve long term liabilities, such as the costs of nuclear decommissioning, PFI and pensions.

PAC wants the Treasury to implement an action plan setting out a co-ordinated strategy to tackle losses from fraud and error, which it described as 'worryingly high'. It also drew attention to the need for greater guidance, particularly in the health and local authority sectors, to ensure full disclosure of 'off-payroll' arrangements and impose appropriate sanctions where there is evidence of tax avoidance.