updated, 18.53

Gardaí have refused to confirm if the failure to prosecute a Fianna Fáil councillor over alleged drink-driving is being investigated.

Earlier the transport minister Paschal Donohoe said he understood the non-prosecution of Limerick councillor Jerry O'Dea was being scrutinised by the Garda Commissioner, Noirin O'Sullivan.

However this evening a Garda spokesman said the force would not comment on the issue as it was an "internal Garda disciplinary matter".

Jerry O'Dea says he fully co-operated with Gardaí after the incident last December - but was told in May he wouldn't be prosecuted.

That's despite newspaper reports that Councillor O'Dea was driving significantly over the legal blood-alcohol limit.

Councillor O'Dea is now the metropolitan mayor of Limerick - but because a summons was not issued within six months of the alleged incident, it can now not be prosecuted at all.

Earlier, our political correspondent Gavan Reilly filed this report for Today FM's National Lunchtime News: