A total of 502,440 names have been deleted from the draft electoral register as part of a major updating campaign that starting during the summer.
New figures from the Department of the Environment also suggest that up to a third of these names may be restored to the register by the closing date of November 25th for amendments to the register.
The latest figures from the Department of the Environment collated from all local authorities across the State show that there are 3.05 million names on the draft register.
Yesterday Minister for the Environment Dick Roche said he now favoured moving towards a "rolling register" where names could be added or deleted continuously throughout the year, as opposed to the current annual system where a draft register is published every November.
He also said measures to prevent electoral fraud would be introduced in specific local areas where it was suspected there were fraudulent names on the register.
These include requiring a large number of voters at specific polling stations to produce identification in order to vote.
Mr Roche is due to appear before a special meeting of the Oireachtas Environment Committee to discuss the draft register.
He is resisting calls from the committee to extend the November 25th closing date for restoring names to the register.
Yesterday Labour party environment spokesman Eamon Gilmore reiterated his party's call for an extension to the November 25th deadline, and for a warning letter to be sent to every person whose name is to be deleted.
"That's less than two weeks away," he said. "In my own local authority area 20,000 names have been deleted, that's one in four. It's quite appropriate that people who have a perfect entitlement to vote be given sufficient time to make sure their name is on the register," Mr Gilmore said.
According to Department of the Environment figures, a total of 502,440 names have now been removed from the register. It is estimated that 170,000 of these have resulted from councils being unable to make contact with anybody at a specific address.
According to provisional figures provided to the Department, local authorities expect to restore tens of thousands of names deleted from the draft register by the November 25th deadline.
Dublin City Council estimates that up to 10,000 names may be restored to the draft register, or one in five of those deleted.
Cork County Council has already received 6,000 corrections to its 40,000 deletions, while South Dublin County Council estimates it will restore up to a third of the 40,000 names it removed from the register.
As part of the review an additional 376,792 people were added on to the register, leaving the draft register at 3.05 million people, or 97.4 per cent of the estimated number of adults in the State.
The lowest levels of registration were in the major urban centres such as Dublin city (80 per cent), Cork (87 per cent) Galway (76 per cent) and Waterford (67 per cent)
The review also showed that the names of many deceased people had been left on the register.
In Dublin city 7,115 deceased persons were removed from the register, 2,130 in Dún Laoghaire and 3,556 in Co Cork. In Waterford 1,400 deceased persons had their names removed.
Yesterday Mr Roche said there was only one local authority area, Louth, where there was an unexplained high number of voters registered there, although he said there was no evidence to date that the cause was electoral fraud.
It is estimated that it is 15 per cent in excess of what should be expected, and he said this would be "the subject of detailed further analysis".
"If it still can't be explained, well there are a range of election-day measures that can be taken," he said.