The software used in the State's electronic voting machines is not secure enough for use, the Commission on Electronic Voting (CEV) has found.
It said that while the machines were reliable and, subject to minor modification, could be used, the software for collating the votes is "inadequate".
It also said security protocols for the transportation and storage of sensitive election information was insufficient.
The long-awaited findings by the independent commission will spark intense political scrutiny, re-igniting the controversy over the €52 million cost of a project.
The Government ruled out using the machines two years ago after a report by the CEV found insufficient testing had been done. They will not be used in the upcoming general election - expected next year - and are costing €700,000 a year to store.
The Government and then minister for the environment and local government Martin Cullen came in for stinging criticism over what was regarded as an ill conceived project that wasted taxpayers' money.
The voting machines and related hardware were of "good quality", the CEV said. "Their design, which is based on voting systems that have been reliable in use elsewhere for some years, has also remained stable since their adaptation for use in Ireland."
It said there should be minor modifications and further testing to the machines but concluded they could be "confidently recommended for use".
The "embedded" software, which controls basic functions such as registering a vote and screen display, was also regarded as sound, but the more complex vote counting software was found to be inadequate.
The report said the security of the computer used for configuring the poll and later counting the votes "is inadequate and needs to be improved".
"Improvements are also required to the security of the methods by which sensitive election data, including votes, are stored, transported and accessed on ballot modules and CDs."
The commission said that many of the improvements would involve "only relatively minor modifications or additions".
The commission, chaired by retired judge Matthew P. Smyth, has concluded its work and is not due to carry out any further examination of the issue. The report was sent to the Ceann Comhairle of the Dáil today.