The British government, which intends to set up a national identity card system, opposes granting the Government full access to its computer records on its citizens once established, it has emerged.
Talks on the ID card system have already taken place between Minister for Justice, Equality and Law Reform Michael McDowell and British home secretary Charles Clarke.
Though the Government does not want to introduce a national identity card system at all, it acknowledges the need for one could become inevitable should the British go ahead.
At present, the British insist they would have access to Irish records, though they are not prepared to let Irish authorities have similar information on UK citizens.
Mr McDowell, who has emphasised his personal opposition to ID cards, has made it clear to Mr Clarke that the Government would require full access to the UK database at "the very minimum", sources have told The Irish Times.
Under the long-standing Common Travel Area arrangement, Irish and UK citizens have been able to travel freely in both directions without needing passports, though most airlines and ferries demand IDs of some kind.
Mr McDowell said yesterday there were "clear implications" for the agreement if the British went ahead with the proposal.
"There are obvious stark implications for Northern Ireland where Irish citizens reside. That is an issue," he told Today FM's Sunday Supplement.
"My own view is consistent in that I do not want to go down the Continental model that a policeman can at any stage, on pain of committing a criminal offence, ask you to produce your identity cards for no reason except that he wants to know who you are.
"I think that would fundamentally change the relationship between the population and the police which serves them. I don't want to go down that road if I can avoid doing so.
"There isn't an ID card system in America, or in most common law countries. The ordinary citizen is left to go about his, or her business unimpeded and if you want to go down to the shops in your shorts on holidays you don't have to carry your ID with you. I don't want to disturb that unnecessarily," said Mr McDowell.
In the House of Commons a fortnight ago, however, Mr Clarke emphasised that UK citizens would not have to carry the ID card at all times, as is required in many Continental countries.
The system, which could take up to 10 years to introduce, could cost over €10 billion to set up, according to a number of estimates. After last Thursday's attacks on London, Mr Clarke conceded that ID cards would not have stopped the bombings, but he insisted they would "help rather than hinder" the subsequent inquiry.
Mr McDowell remained dubious, even on the latter point: "If there are indigenous populations the question of ID cards is hardly likely to affect their operation one way, or the other.
"If there are extremists among us the fact that they carry a card, or don't carry a card is not going to be of huge significance on whether they engage in terrorist activity and whether they are detected doing so."