The Commission for Communications Regulation (ComReg) will investigate whether RTÉ Transmission Networks Ltd discriminates against competing broadcasters when offering transmission capacity.
RTÉ Transmission Networks is a division of the State broadcaster, which operates the national transmission system. It was recently separated from the broadcaster as part of a failed attempt to sell off its network.
The investigation will review the fees that the standalone subsidiary charges independent firms, such as TV3 and Today FM, to ensure they are not paying proportionately more than other RTÉ channels or TG4.
TV3 recently complained to the Government that it was being charged three times more than TG4 for its transmission service despite receiving less capacity.
ComReg made the announcement yesterday as part of a major review of the broadcasting and mobile market to take account of the European Union's new communications regulatory regime.
Under this regime, ComReg will, for the first time, have the power to intervene in certain parts of the mobile phone market such as roaming and call termination if they are not competitive.
Earlier this month, ComReg told an Oireachtas committee that Irish mobile phone charges were among the highest in the world. It said it could use regulation to force prices down if it decided the market was not yet competitive following the review.
In a document published yesterday, ComReg again says there is evidence that voice-call termination rates are above the competitive level and regulatory intervention will be required.
ComReg also says it is reviewing the roaming market in co-ordination with other European regulators.
It will also assist other European regulators to gather data on the four Irish mobile phone firms, according to the market review document.
If the regulator decides to take regulatory action against mobile firms, it must receive the assent of the European Commission.
Meanwhile, ComReg said yesterday it would not review the wholesale satellite or cable television markets in the Republic because they would "tend, over time, to become competitive."
