Sinn Féin's Lynn Boylan said the report found Ireland has "one of the most concentrated media markets of any democracy"
A new report has recommended a Commission of Inquiry into media ownership in Ireland.
The study was commissioned by Sinn Féin MEP Lynn Boylan, and carried out by two independent legal firms.
It raises concerns about the high level of media ownership by businessman Denis O'Brien, as a result of his "significant minority stake" in Independent News and Media and "substantial holdings" in commercial radio.
It also recommends that a Commission of Inquiry looks at the role of RTÉ as a public service broadcaster, and what is described as the "chilling effect" of current defamation laws.
The report authors conclude that they "anticipate that the Commission will at the outset need to grapple with the question of what definition of media pluralism to adopt, and to consider and systematically identify which concrete indicators it considers necessary in order to measure media pluralism in Ireland".
Speaking as she launched the report this afternoon, Lynn Boylan observed: "This report has found that we have one of the most concentrated media markets of any democracy, with the two most controlling entities being the national state broadcaster, RTÉ and one individual business in the private sphere.
"I believe that it is now time to establish the multi-disciplinary commission of inquiry to look at the media landscape in Ireland as called for by the NUJ [National Union of Journalists]," she added.
Séamus Dooley of the NUJ welcomed the call for a commission, stating: "We believe that the Government must show leadership in setting up a commission on the future of the media in Ireland.
"Central to that debate is the issue of ownership and control but we also need to examine wider issues, including access to employment, barriers to diversity in journalism, the gender pay gap, the precarious nature of employment within the media and the specific issues confronting local media organisations," he added.
The report's publication has also been welcomed by the Social Democrats, who have proposed a bill on the subject of media ownership in Ireland.
Catherine Murphy TD said: "Freedom of the press is vital if we are to be able to hold those in positions of power to account and allow for healthy discussion and dissent in Irish public life [...] The tabling of this legislation will be another step forward in our campaign for a free and diverse media in Ireland."