Minister for Communications Denis Naughten has referred Independent News and Media's proposed acquisition of local newspaper group Celtic Media Newspapers to a further assessment.
The Phase 2 assessment will be undertaken by the Broadcasting Authority of Ireland, who will provide a report and recommendation to the Minister within 80 working days.
Mr Naughten will appoint an advisory panel to provide an opinion to the BAI.
The National Union of Journalists has welcomed the Minister’s decision.
In a statement, Irish Secretary Seamus Dooley supported what he said was "a highly significant decision about a matter of great public importance".
He said: "This is a welcome development and we will be making a comprehensive submission. We welcome the decision to appoint a panel and look forward to the deliberations of the Oireachtas committee.
"We would encourage the committee to meet in public and to call witnesses before forming a view on this matter.
"Recent developments at INM - both in relation to corporate governance and staff pension schemes, are appropriate to the terms of reference of this review."