A Government scheme to help cash-strapped departments make long term savings was unimaginative, lacked focus and may not have served its purpose, according to an audit office report.
The Invest To Save fund was set up by the Stormont Executive in 2010 to help deal with the upfront costs of efficiency savings.
But, even though £311 million was ring-fenced for 31 projects and should not have been used for any other purpose, much of the money was re-directed to mitigate front-line financial pressures within health and on the roads.
Auditor General Kieran Donnelly said: "In times of austerity, initiatives of this nature offer particular opportunities to innovate and to use taxpayers' money to best effect.
"The primary focus of Invest to Save funding was on delivering savings. However, almost one third of projects did not anticipate and/or quantify savings and no specific savings targets were set, monitored or reported on for the schemes as a whole.
"Whilst not disputing the merits of the projects which were funded, it is not clear how many met the criteria."
Almost two thirds of the money (£206 million) was allocated to the Departments of Health and Regional Development.
The report said it was difficult to identify boundaries between Invest to Save funding and conventional funding and whether it could or should have been secured through the normal bidding process.
The auditor said this was particularly evident in the case of the £108 million provided for the Department of Regional Development's road structural maintenance programme which received more than a third of Invest to Save funding.
The report also noted that a lack of central monitoring, validation or reporting of savings to the Assembly which meant it was "difficult" to assess the effectiveness of the scheme.
Although some departments delivered significant savings, the auditor said information provided to his office was inconsistent.
More than £100 million of savings were through six staff efficiency schemes while the Department for Agriculture and Rural Development also reported that £41.2 million of EU fines had been avoided because money was allocated to their EU Audit Compliance Programme.
The report found little evidence to show that Invest to Save was used sufficiently to encourage risk-taking and innovation.
The scheme did not deliver the same focus as similar projects rolled out in England and Wales, it was claimed.
Meanwhile, the auditor said there was more scope to take advantage of new technology to identify alternative and more effective ways to operate.
Mr Donnelly said: "Drives for improved efficiency in the delivery of public services often require upfront investment to deliver longer term savings. It is important that effective assessment, monitoring and reporting arrangements are in place. Otherwise there is a risk that the funding does not achieve the financial and service delivery benefits intended and that the potential to encourage transformation and innovation across public services is not maximised."