The Irish Council for Civil Liberties has criticised a Cabinet direction last April ordering phone companies to retain the telephone call records of Irish citizens for three years.
The Data Protection Commissioner, Mr Joe Meade, has also expressed concern that the direction - details of which emerged at a forum on data retention last week - was subject to neither Oireachtas nor judicial review.
The ICCL and several legal sources have told The Irish Times that it appeared the Government had secretly placed interception orders for data traffic on the State's entire population.
However, the Department of Justice yesterday rejected this view.
A spokesman said that data traffic retention - retaining records on when and where calls were made, by and to whom, and for how long - was different from data interception - the retention of the content of calls or faxes - and said the State was allowed to retain data traffic.
But no laws exist yet which allow the mass retention of data traffic.
Last year's direction was made using laws intended for the surveillance of individuals suspected of committing a crime.
It was issued a month before the general election by then minister for public enterprise, Ms O'Rourke, on the instruction of then minister for justice, Mr O'Donoghue, following a Cabinet decision.
The power to issue the direction was partially based on a section of the 1983 Postal and Telecommunications Services Act.
This Act was extensively revised to limit ministerial power to order surveillance, after it emerged that the State had placed phone taps on several journalists' telephones.
It is also based on sections of the Interception of Postal Packets and Telecommunications Messages (Regulation) Act, 1993 - a revision of the 1983 Act which explicitly requires judicial oversight when personal privacy might be compromised. The two Acts were designed to allow the collection of communications data from individuals believed to be guilty of a criminal offence.
Mr Malachy Murphy, of the Irish Council for Civil Liberties, said the fact this was done in secret was a serious cause for concern.
Mr Meade told the forum last week that telecommunications companies were explicitly told not to reveal the direction.
He said he was unhappy with the order in part because "it would have remained confidential until a minister chose to reveal it".
The Departments of Communications and Justice each said that questions on the matter should be referred to the other's Department.
University of Limerick law professor, Mr Dermot Walsh, who has written on the 1983 and 1993 Acts as well as a book on constitutional law, said the basis for the direction went beyond the scope of the Acts.
The original laws were directed at individuals suspected of involvement in a crime, allowing law enforcement to conduct surveillance on that individual as calls were being made, he said.
They were not for "interception [after the fact] of all citizens' data traffic, to be held for several years", he added.
The direction was issued after Mr Meade challenged the practice by telephone companies of retaining call records for up to six years, which, they said, was necessary to conform to the Statute of Limitations. He recommended a retention period of six months instead, and said the companies were not legally required to retain records at all.
