More than £120 million (€174 million) is estimated to have been lost through fraud and error in welfare payments in Northern Ireland in the year to 2005.
The Comptroller and Auditor General's report out today also estimated that up to £3.3 million in grants was given in which there was "insufficient evidence of compliance with the required procurement procedures".
The report says a qualified audit opinion on the spending of £66 million (€95.6 million) on community and urban development grants is due because of "weakness in financial control and monitoring expenditure".
John Dowdall, Comptroller and Auditor General for Northern Ireland and head of the Audit Office, found four aspects of governance arrangements that need to be developed in the central government sector.
He reported that members of various boards should have the appropriate skills, expertise and understanding of their role and that the inclusion of independent non-executive members with relevant skills would help bring about what he called "an effective challenge function".
Mr Dowdall called for the promotion of a "risk-management culture" and for the establishment of "correct governance arrangements between government departments and their sponsored bodies".
The report also refers to the Northern Ireland Child Support Agency, Invest Northern Ireland and the Education and Library Boards.
Mr Dowdall said the Belfast board as well as the South Eastern board had run up significant deficits. "It is unacceptable that the Belfast Education and Library Board overspending in 2001-2 only came to light so recently and that the scale of overspending in 2003-4 could not be determined accurately for so long," the report says.
It notes the South Eastern board's cumulative deficit currently stands at £21.6 million (€31.3 million) but adds its accounts have not been finalised.