The notion that RTÉ is politically biased makes little sense, the chair of its board Moya Doherty has said.

It would fundamentally destroy trust in the broadcaster and would not be tolerated by the regulator or by law, she told the Joint Oireachtas Committee on Transport and Communications.

RTÉ was appearing before the committee on Wednesday to discuss measures in place to prevent political bias in their programming and reporting.

She said the national broadcaster was not there to serve the interests of share holders, wealthy owners or private equity firms but rather the public with “clear statutory obligations and appropriate regulation in governance”.

When serious editorial mistakes were made a number of years ago at the broadcaster, she said it was an issue of “such concern both inside and outside RTÉ” it lead to a thorough review of all editorial processes.

RTÉ deputy director general Kevin Bakhurst and managing editor of current affairs on television David Nally dismissed suggestions by Fianna Fáil's Michael Moynihan that bias had been shown on the Claire Byrne Live show by not inviting any member of his party on it during the first few weeks of its run.

Mr Bakhurst said there had been an interview bid in for party leader Micháel Martin for weeks and that it was up to Fianna Fáil to decide when he would appear.

David Nally said programmes needed to be judged over time and not “freeze framed” over a six week period. He said he was very happy that the share out of appearances on current affairs programmes was very fair and that tabs were kept on this.

Mr Bakhurst said the broadcaster also kept track of who appeared on their light entertainment shows such as the Late Late Show and the Saturday Night Show to make sure there was a fair range of views presented.

He dismissed suggestions that groupthink existed at the broadcaster saying it “simply isn’t there” and that robust debate was encouraged at editorial meetings.

Fine Gael TD Patrick O'Donovan said the broadcaster was guilty of ignoring the regions saying the Limerick City of Culture celebrations, for example, had been an afterthought mention on all bulletins "but if you put two pigs flying up O'Connell Street [in Dublin]it would be the number one item on all bulletins".

Mr Bakhurst said a full piece was given over to the Limerick celebrations on a Friday evening but admitted that a second piece should have been done over the weekend given the crowds attending.

He denied information had to be “dragged out of” the broadcaster in relation to what presenters are paid.

“We do disclose what presenters are paid. We don’t cover it up... We release it with a time-lag because it is a very competitive marketplace and if we go out and say what we pay people now they would be picked off one by one,” he said.

Mr O’Donovan said there had been wall to wall coverage of political nepotism recently and asked whether the problem existed at the broadcaster.

Mr Bakhurst said he was confident nepotism did not exist at RTÉ and that he would not stand for it.

Labour TD Michael McCarthy asked what the broadcaster's plan was to have proper balance in its coverage in the run up to the marriage equality referendum in May.

Mr Bakhurst said they had to represent in a balanced fashion the debate that was going on but that it was problematic for them to find a “wide range of voices”.

“There are a limited number of voices on this one who are prepared to speak against the proposed referendum.. It is a problem for us to to find wider range of voices and we end up falling back on familiar voices,” he said.