Nearly one-in-five crimes reported to gardai in 2011 were not recorded on its Pulse system, a review by the Central Statistics Office (CSO) has found.
The agency gathers data and statistics that are often used as the raw material for major government decisions.
It also found that 7pc of incidents classified to a non-crime category on the garda computer system in the same year should have been recorded as a crime instead.
Around 3pc of crimes recorded in Pulse in 2011 were deemed to have been incorrectly classified to the wrong crime category, while a further 4pc of cases had insufficient information to determine the correct classification.
The CSO stopped publishing crime statistics in the middle of last year over concerns that the figures were incorrect.
It then chose to scrutinise the figures from the year 2011 as part of its assessment of issues highlighted in the November 2014 Report of the Garda Inspectorate on Crime Investigation, which found significant shortcomings in the way offences were recorded.
The report found substantial evidence of serious crime, like assault, burglary, robbery and theft, were being "under- recorded" by as much as 30pc in some garda divisions.
One common practice highlighted in the Inspectorate report was for incidents of theft - very often of mobile phones - which were re-classified as "lost".
The CSO reviewed its process and the systems for recording crime in the wake of that report, including how data was recorded on the garda Pulse system.
The CSO has now decided to resume issuing crime statistics on a quarterly basis.
Justice Minister Frances Fitzgerald (inset) welcomed the resumption of publication of the official Recorded Crime Statistics, together with the publication by the CSO of its analysis of the issues arising from the 2014 Garda Inspectorate Report on Crime Investigation.
"It is vital that we have access to accurate, reliable data on crime. I expect nothing less," she said.
"Quality data is critical to ensuring that the policing services offered by An Garda Siochana are responsive to emerging and latest crime trends," she added.