It has also emerged that the broadcaster has begun experimenting with another digital radio system, Digital Radio Mondiale (DRM), which is seen by some as the digital successor to standard AM and long wave broadcasts.

RTE's DAB licence application, which has been made in the past two weeks, comes just four months after RTE officially launched its digital radio trials.

Comreg is expected to make a decision on the application in early 2008 but Mick Kehoe, executive director of RTE Networks (RTENL), which operates the state's broadcasting transmission network, said there was no official timetable for the launch of a national digital radio service.

Kehoe said RTE would decide whether or not to start operating a service later this year when the first results of its DAB trials have been analysed.

"The question is: are people listening? The feedback from the trial seems good to date but we won't know fully until we complete our research."

If the research results are positive, it is likely that RTE will operate a digital radio system similar to its current trial, which can be received in the Dublin and Dundalk areas and features RTE's four national stations along with four additional RTE digital channels.

Kehoe also revealed that RTENL begun experimental DRM transmissions last week on RTE's long wave 252khz frequency. He said, however, that these were strictly technical trials and that there was no intention to start regular DRM transmissions in the near future.

"We've been looking at range and signal quality. We've been recording 252khz from a number of locations. We've been doing some recording in London and Evesham in the UK, Ballydavid in County Kerry and Derrybeg in north Donegal."

Kehoe said RTENL had experimented with transmitting multiple channels on the frequency and a ticker tape-style system which would offer rolling news headlines on DRM radio displays.

"We're just testing out the potential of the system but there are issues because no one is mass-producing DRM receivers at the moment, " he said.