TV3 last night condemned Communications Minister Pat Carey's decision to approve RTE's proposed five "free to air" channels as part of the Digital Terrestrial Television roll-out.
TV3 said it was "shocked" that the state broadcaster would be allowed to run the new TV channels.
Yesterday, Mr Carey approved the roll-out of high definition RTE Two HD Select, RTE Aertel Digital, children's station RTE jr, catch-up channel RTE Plus and RTE News Now.
The Broadcasting Act requires the minister to conduct a review of any new services or channels proposed by RTE prior to granting consent. It also requires the Broadcasting Authority of Ireland to assess the impact of these services on the broader broadcast and media sector.
Mr Carey said he had approved the services after "a thorough examination of the proposals" made by RTE.
However, a spokesman for TV3 said: "These newly approved channels will extend RTE's dominance in media when it is already the most dominant state broadcaster in Europe. RTE will further increase its share of the advertising market alongside its total dominance of the licence fee.
"This comes at a time when commercial media is on its knees due to a media market crash, which has been exacerbated by below-cost selling of advertising.
"The timing of this announcement, two days before a General Election, raises serious questions," he added.
RTE welcomed the decision, with the broadcaster's director of digital switchover Mary Curtis saying: "The Saorview channel and service line represents great news for Irish television viewers.
"For the approximately 340,000 households who currently receive just the four main free-to-air TV channels, this represents a significant increase in choice."
The freeview service will start at the end of May. A publicity campaign will start in the middle of next month.