Fianna Fáil Justice Spokesperson Niall Collins has said it is a “source of genuine regret” if writing a letter to the courts pleading for leniency for a convicted drug dealer suggested “anything other than total respect for judicial independence”.

In a statement, he said: "There has been considerable and understandable media comment about my decision to write a letter to the court considering the case of an individual convicted of an offence in Limerick.

“While I would have preferred to avoid comment until the conclusion of this case, the level of public interest prevents this.

"I fully understand and respect the absolute independence of any sentencing judge in making their decision based on the facts put before them during any trial.

“If my actions suggest anything other than total respect for judicial independence that is a source of genuine regret".

He said he wrote the letter outlining the exceptional circumstances of the family as the mother of the man’s four children had died earlier this year.

He continued: “I truly believed that the Judge should be made aware of these tragic circumstances so that they could be taken into consideration when sentencing.

“My decision was based solely on compassion and concern for the four children.”

The Limerick TD wrote a letter that was brought to the attention to Judge Carroll Moran who was adjudicating on a case at Limerick Circuit Court involving a 40-year-old widower and father-of-four.

Hugo Porter, of Castleconnell in Co Limerick, pleaded guilty to possession of cannabis worth almost €18,000 in a field in Limerick in June 2011.

Mr Collins' letter was one of a number of documents presented to Judge Moran by Mr Porter's defence team during a sentencing hearing this week.

The letter was not read out in court but was referred to when seeking leniency on the basis that Mr Porter's wife had died tragically, that he was the only carer of his children, and that this made the case an exceptional one.

Mr Collins this morning said he knew what he was doing and that there was no political gain in it for him, as the convicted man in question is not a constituent.

He said this was not similar or the same as matters in the past when ministers had to resign about inappropriate approaches to judges.

Mr Collins said he was not approaching a judge in secret in his chambers and added that the letter was presented in open court.

He said he will make the appropriate comments in October when the sentencing matter is concluded. Mr Collins is in the Dáil today.

Sources close to Mr Collins earlier said he had acted out of humanitarian motives.

Taoiseach Enda Kenny has criticised Mr Collins over the letter.

Speaking to reporters in Dublin, Mr Kenny described the communication as a "very serious matter" and a "direct intervention in the administration of justice".

He said the matter needed to be explained urgently by Mr Collins and Fianna Fáil leader Micheál Martin.

Sinn Féin leader Gerry Adams has said it was not an appropriate intervention, despite the fact that there might have been very good family reasons for the Limerick TD to have become involved.

LImerick Sinn Féin Cllr Maurice Quinlivan has called on Mr Collins to consider his position as Fianna Fáil Justice spokesperson and for the party leader Mr Martin to remove him if he fails to resign from his frontbench position.

Mr Quinvilan said Mr Collins' actions were a slap in the face to gardaí who have done their work and a slap in the face to the communities in Limerick who are destroyed by drugs.

Reform Alliance TD Lucinda Creighton has said there were no circumstances in which a TD should write a letter seeking clemency or a lighter sentence for a defendant.

Speaking on RTÉ's News At One, she said such action is completely inappropriate and breaches the constitutional provision in respect of the separation of powers.