A high-level group has been established to review access to confidential information, following leaks from the Department of Social and Family Affairs, the Dáil was told.
Minister for Social and Family Affairs Martin Cullen said prosecutions fell under the remit of the Data Protection Commissioner and an official had been sacked.
"The action taken has been quite severe; people have lost their jobs."
Mr Cullen was replying to Fine Gael spokeswoman Olwyn Enright, who asked what plans the Minister had to detect improper access in the future.
"I am concerned that the department did not know about these two cases until the Garda informed it of one case and it was informed by one of the people whose name appeared in a newspaper of the other."
Mr Cullen said there had been been only three cases since 2002.
"Given the scale of the operations of the department, the number of customers and the number of operations carried out on a daily or weekly basis, that number is relatively small, although they are serious matters.
"In the first case referred to by the deputy, the official has been dismissed. In the second case, the official resigned before disciplinary action could be taken by the department. In another case, of a less serious nature, the officials involved were cautioned about their conduct and this was noted in their personal files."
Referring to a case of a woman who won the National Lottery prize, Ms Enright said 106 officials had looked up her file.
"This means that 106 officials abused their position. I would not consider that breach as of a less serious nature. I am sure the Minister agrees that staff are not engaged to look up people's private information for their own amusement."
Mr Cullen said he understood the number of officials involved was 74. There were only three cases, although he did not want to minimise their importance.
