The BCI's director of broadcasting, Celene Craig, said that although it seemed possible to achieve the 2012 target, "it is obviously dependent on a number of factors including interest from operators, whether it is possible to build the infrastructure on time and potential legal challenges".

Craig admitted that the BCI would miss a statutory requirement introduced in April's Broadcasting Act to start licensing operators this October.

However, she said it should be in a position to start the process early next year.

"The date in the act is not an absolute stipulation and you have to remember that a significant piece of policy development can usually take 12 to 15 months and, to start the process next year, we have compressed this into seven and a half months, " she said.

DTT involves the use of digital signals to offer more channels and better picture quality, including high definition (HD) broadcasts, using a conventional TV aerial.

It will also allow broadcasters to cease transmitting standard terrestrial television signals and dedicate the spectrum to other purposes. Ireland has lagged behind other European countries on the DTT issue, particularly Britain, which is due to start switching off its analogue TV signals next year.

Last month, the BCI announced that it was postponing the licensing process for three local radio stations to focus on DTT. Under the DTT process, the BCI will award licences to three digital operators, which will each provide four to eight channels to the state's DTT service.

Under the DTT scheme, RTE will automatically receive enough spectrum to broadcast between four to eight digital TV channels. The station is already starting to plan for its DTT service.

According to Anne O'Connor, special advisor to RTE's director general, the state broadcaster believes that DTT will offer significant advantages to viewers over standard analogue broadcasts.

"In particular, we see a significant HD opportunity in Ireland. In the UK, they don't have enough DTT spectrum space to allocate HD channels whereas HD will be available from the start in Ireland, " she said.

O'Connor said that RTE also hoped to offer interactive services, video on demand and a listing guide as part of its DTT service. "We're also looking at improving accessibility by looking at offering audio description and possibly signing, which are possible on digital TV but not analogue."

The Department of Communications is currently operating a DTT trial in Dublin and Louth, which is due to end next year. Last week, Setanta Ireland and Setanta Golf were added to the selection 16 TV channels, 12 radio channels and one High Definition TV channel running in the pilot programme.

The Minister for Communications, Eamon Ryan, has said he wants significant progress towards introducing a national DTT service by the end of the trial.

"We don't want to put it off until 2012 because that would put Ireland at a significant disadvantage compared to our European neighbours in terms of telecommunications, " he said.

Tony Killeen, minister of state for Communications said last week that Ireland must complete the transmission from analogue to digital broadcasting before the EU's 2012 deadline.

"I expect the development of a national public service and commercial deployment of digital terrestrial TV services in mid 2008, " he said.