The Taoiseach has insisted the Public Services Card is not a national identity card.
Around 2.75 million cards have been issued, and the card is currently used to access services such as collecting welfare payments.
There are plans for the card to be mandatory for many services, including applying for or renewing a passport.
Debate over the card intensified last week after Social Protection Minister Regina Doherty said the new card is not mandatory - but added that it is compulsory if you want to claim benefits from her department.
There have also been concerns about the data protection issues involved in sharing information stored on the card across Government departments.
The information stored on the card could be supplied to 50 different state bodies.
In an article for The Irish Times today, Finance & Public Expenditure Minister Paschal Donohoe argued: "The PSC is absolutely not an attempt to bring in a national identity card, by stealth or otherwise."
Taoiseach Leo Varadkar also today defended its introduction.
He argued: "It is not a national ID card. We have absolutely no plans to introduce a national ID card in Ireland - it's something I wouldn't be in favour of.
"A characteristic of a national ID card is that the police or the army can ask you to produce it, that you use it for travel. That's not going to be the case."
Mr Varadkar also said officials will consider any potential concerns the Data Protection Commissioner has about the card.
He observed: "Certainly the Government will respond to any concerns that the Data Protection Commissioner makes.
"It is important to say, though, that there is a legislative basis for the Public Service Card - it's there in the [Social Welfare Consolidation Act, 2005]."