Fianna Fáil TD Willie O'Dea has been slapped down by his party colleagues after jumping to the defence of billionaire businessman Denis O'Brien.

Mr O'Dea insisted that Mr O'Brien was constitutionally entitled to challenge a ruling by the Dáil's Committee on Procedures and Privilege (CPP) relating to comments made by Social Democrats TD Catherine Murphy.

But in doing so, Mr O'Dea directly contradicted his party leader Micheál Martin, who had warned that Mr O'Brien's legal challenge posed a threat to parliamentary democracy.

And yesterday senior Fianna Fáil figures weighed in behind Mr Martin in raising concerns about the telecoms tycoon's High Court action against TDs and civil servants involved in the CPP.

Fianna Fáil Clare TD Timmy Dooley said Mr O'Brien's legal action was an "affront to democracy".

"Whilst in general context everyone is entitled to a fair hearing before the law, I think on this one Denis O'Brien would have been wiser to keep his wig and gown in his drawer," Mr Dooley told the Irish Independent.

Fianna Fáil Cork North West TD Michael Moynihan said the courts had "stood by democracy" in the past and he hoped they would do so again in this instance.

A Fianna Fáil source said the party and Mr Martin stood by his call for Mr O'Brien to "back off" and stop his legal action against elected representatives.

Taoiseach Enda Kenny also came out in support of the elected representatives, saying: "Freedom of speech is a fundamental right."

He added: "I respect the CPP's right to make all its adjudications and I fully support them in their oversight role within the Oireachtas."

Mr O'Brien has alleged that the CPP has breached his constitutional rights by failing to reprimand Ms Murphy and Sinn Féin TD Pearse Doherty after they detailed his alleged banking affairs with the Irish Bank Resolution Company (IBRC.) in the Dáil.

Mr O'Brien's solicitors insist that the CPP should have ruled against the TD's, and argue that their comments interfered with a legal action he had taken against RTÉ over a proposed broadcast outlining his alleged personal banking arrangements with IBRC.

William Fry solicitors claim that when the CPP ruled in favour of Ms Murphy, following a complaint by Mr O'Brien, it used an "erroneous interpretation" of Oireachtas rules relating to Dáil privilege.

Mr O'Brien's legal team claim the ruling was made "without any evidence that Ms Murphy acted in good faith". He is seeking costs for the case.

The CPP will meet to discuss the claims in the coming weeks and decide the next course of action to take. An Oireachtas spokesperson was unable to establish if the taxpayer will pay the deputies' legal fees.

Irish Independent