Figures seen by RTÉ News show the economy shrank by 1.1% in the first three months of the year compared to the final quarter of 2011.
The National Accounts, due to be published tomorrow, show a drop in net exports and in personal consumption were the main reasons for the fall.
Government spending and capital investment were up on a seasonally adjusted basis.
The figures also mean the economic performance for last year is better than had been thought earlier.
The CSO revised upward its growth estimate for the fourth quarter of 2011 to 0.7% of GDP, compared to a previous figure of -0.2%.
As a result, the full year growth figure for 2011 was stronger than previously thought at 1.4%, compared with an earlier estimate of 0.7%.
The figures from the CSO are keenly watched by investors as a gauge of the health of the Irish economy.
There was a big drop in output in the distribution, transport software and communications sector, which decreased 9.7% between the first quarter of 2011 and the corresponding period this year.
Agriculture, fishing and forestry fell 0.7% over the same period, while public administration fell 2.3%. Industry grew by 2.2% and services grew by 1.5% compared with a year earlier.
Personal spending fell by 2.2%, while government spending fell by 3.3%. Capital investment increased by 8% compared with the first quarter of 2011, and there was a large increase in net exports (exports minus imports) of + €1.99 billion.
Central Statistics Office Statement
The Central Statistics Office issued a statement this evening stating that the Quarterly National Accounts release for the first quarter of 2012 was inadvertently published on the CSO website for a 15 minute period this afternoon.
CSO understands that news media gained access to the release during this short period, the statement continues, "Notwithstanding this, CSO has decided to adhere to its pre-determined release time."
CSO apologised for any inconvenience caused to its users.
