The Office of the Data Protection Commissioner is in discussions with an Irish Genealogy website which left personal data open to identity thieves.
Information including a date of birth, an area where someone grew up and their mother's maiden name were put online.
IrishGenealogy.ie, which is run by the Department of Arts, Heritage and the Gaeltacht, removed the information as soon as concerns were highlighted.
John O'Dwyer, Deputy Commissioner with the Data Protection Office, said the website should have been more careful.
"They took the appropriate action once it was brought to their attention. However, we would have expected they would have been more conscious, putting personal data available like that."