Further expansion of the Dublin radio market is becoming increasingly unlikely due to a lack of space on the FM radio spectrum, the Broadcasting Commission of Ireland (BCI) has said.

The BCI, which now regulates 28 commercial stations, said while new stations could be licenced for the AM band, there were increasing capacity problems on FM, which is the most popular band. The BCI and ComReg - the Telecommunications Regulator - are studying options to find additional space on the spectrum.

However no major changes are expected for some time, as engineers are still working on the problem, according to a BCI spokeswoman.

The problem is most acute in Dublin where RTÉ, Today FM and a large number of commercial and community stations currently share the spectrum.

The BCI allocates blocks on the spectrum according to a long-standing policy, but in recent years getting new licencees sufficient space has proven difficult.

The largest block lies between 87.5 and 94.5 and is earmarked for public service stations, mainly RTÉ and its subsidiaries.

The rest of the spectrum is taken up with independent radio operations, further public service space and space for the national operator Today FM.

The BCI is currently licensing several local stations, but after completing that it is uncertain how many more can be licensed.

The BCI's own future is unclear at this stage, with the Minister for Communications, Marine and Natural Resources, Mr Ahern, seeking to set up a new Broadcasting Authority for Ireland (BAI). It is likely the BCI will be subsumed into this organisation, with all staff transferring.