Concentration of media ownership in Ireland poses a "high risk" to diversity of opinion, according to a report compiled by a Dublin City University lecturer.
Fewer owners limit the opportunity for diversity of opinion and freedom of expression and the report put the risk of this at 74 per cent.
However, the risk to diversity is deemed “medium” or a 50 per cent rate, when it comes to cross-media ownership, where one individual or company controls media across two or more sectors.
The risk is lower, at 38 per cent, when it comes to transparency in media ownership.
Irish media and competition law, according to the report's author Dr Roderick Flynn, imposed no maximum media thresholds and there was "nothing in Irish law to stop an individual or institution enjoying 100 per cent ownership of newspapers, radio or TV stations".
The 2014 Competition and Consumer Protection Act points to the “undesirability of allowing any one undertaking to hold significant interests, a 20 per cent share, within a sector, or across different sectors”.
The report calls for the Act to apply retrospectively and Dr Flynn said this had been done to allow “free-to-air” viewing of certain football matches after Sky TV had secured broadcasting rights.
"To date, Irish politicians have been reluctant to seriously consider this, however, citing the strong defence of property rights that characterises the Constitution,'' the report Media Pluralism in Ireland, states.
“However, given that freedom of expression is also explicitly defended in the Constitution, there is clearly a case to be made for retrospection.’’
Other EU states impose absolute limits on ownership. In Germany, 20 per cent is the ownership limit in any media sector and where that limit is breached, “forcible divesting” is imposed.
Businessman Denis O'Brien, the report said, enjoyed a dominant position within the print and commercial radio sector, owning 29.9 per cent of Independent News and Media (INM) and as chairman and principal shareholder of Communicorp, which accounted for 20 per cent of the Irish radio market.
However, this was countered by RTÉ’s dominant position in both television and radio markets.
It said there were several other “notable’’ examples of cross-media ownership, such as Landmark Media (formerly Thomas Crosbie Holdings) and UTV Plc.
The report said company law required media outlets to notify the Commission for Consumer Protection and Competition about any proposed changes. However, it did not require media firms to make public their ownership structures.