His comments come as a meeting was held in INM last night, where staff was reassured that newspapers and online operations were separate to issues surrounding governance and the boardroom.
It emerged earlier this week that a number of high-profile journalists, including Sunday Independent deputy editor Brendan O’Connor, ex-Independent journalist Sam Smyth, and Sunday Independent investigative journalist Maeve Sheehan, are among a group of 19 individuals whose data and information was accessed on INM’s internal systems in 2014.
Also on the list, detailed in a High Court affidavit prepared by the Director of Corporate Enforcement, Ian Drennan, are INM’s former director of corporate affairs Karl Brophy, former CEO Vincent Crowley, former finance director Donal Buggy, and former CEO of its Irish division, Joe Webb.
Two barristers, Jacqueline O’Brien and Jerry Healy, who worked on the Moriarty Tribunal, are also on the list.
Mr Drennan has asked the High Court to appoint inspectors to INM to investigate the breach.
The case is due to be heard on April 16.
The Data Protection Commissioner has already confirmed that she will investigate whether personal data was accessed in the alleged data breach.
In a statement, the DPC said it will examine if data was processed in accordance with data protection legislation.
It said it was establishing the parameters of the investigation, including seeking additional information from INM on foot of the breach notification it filed with the office last week.
Speaking on RTÉ’s Morning Ireland, Mr Feeney said the alleged access of reporters’ emails by an external company was “deeply disturbing” and undermined investigative journalism.
“It is deeply disturbing that communications between journalists and third parties can be accessed and used for purposes other than which they originated.
“This gets to the core of investigative journalism in the sense that it endangers the confidentiality that a journalist may guarantee someone if they are giving them information which may be important to bring into the public domain.
“It undermines investigative journalism and therefore it is of deep, deep concern,” he said.