Micheál Martin was speaking after the man was given a death sentence in Lebanon over the killing. Private Rooney, 24, from Newtowncunningham in Co. Donegal, was killed when a convoy of Irish troops serving with a UN peacekeeping force was ambushed and fired upon on December 14, 2022.

The shooting happened near the town of Al-Aqbiya in the south of Lebanon, which is a stronghold of Hezbollah. Pte Rooney, from the 121 Infantry Battalion of the Irish Defence Forces, was killed during the incident.

The Taoiseach said that a number of people had been convicted in relation to his murder, but some of the sentences were "unduly lenient".

"The main culprit was at large and that is very, very regrettable," the Fianna Fáil leader said ahead of a Cabinet meeting, adding: "The delay that it has taken to have justice has been far too long and I must say that some of the sentences are unduly lenient as well in respect of others."

On Monday, the Government was informed of the completion of a military tribunal in Beirut for those indicted for the murder of Pte Rooney. The Taoiseach said yesterday: "Peacekeeping is a very noble cause, and Private Seán Rooney gave his life to the cause of peacekeeping and to protect others.

 Taoiseach Micheál Martin.

 Taoiseach Micheál Martin.

"I’ve said repeatedly to the Lebanese authorities that the nobility of the role of the peacekeeper must always be reflected in terms of bringing those who are responsible for this murder to justice, and we will continue to make that point."

Mr Martin also said death sentences in Lebanon had not been applied for "quite some time" and that the expectation is that it will be commuted.

The Taoiseach said: "Overall, those responsible had escaped, if you like, justice for far too long. Many are at large for quite some time and the main individual now is at large as well, and that is very unsatisfactory."

He added: "The court has made its decision, we can’t interfere in the operation of the court itself. But I think the whole process certainly left a lot to be desired."

Private Sean Rooney.

Private Sean Rooney.

On Monday, Tánaiste and Foreign Affairs Minister Simon Harris said he had been informed of the completion of the military tribunal in Beirut for those indicted for the murder of Pte Rooney.

"I welcome the conviction of the main defendant and a number of the other defendants, who had not previously been in court," he said.

"While noting the sentence handed down to the main defendant, I am disappointed and share the disappointment of Pte Rooney’s family at the lighter sentences imposed on a number of those convicted today.

"Seán Rooney made the ultimate sacrifice in the noble pursuit of peace. This is a difficult time for his family and his colleagues, especially those who were injured that night. All our thoughts are with them at this time."

 The Tánaiste said he pressed the case during his visit to Beirut in March, in meetings with the Lebanese ministers for foreign affairs and defence.

"I raised, in the strongest terms, my deep frustration at the slow pace of proceedings before the Lebanese military tribunal concerning those charged with Pte Rooney’s killing,’ he said. ‘I appreciate, therefore, the efforts of the court to bring forward the hearing date from September to today [Monday].

"During my visit to Beirut, I left the Lebanese ministers in no doubt as to the absolute determination of the Irish Government to ensure that those responsible for Private Rooney’s death are brought to justice.

 "I want to express my appreciation to my officials, members of the Defence Forces, Ireland’s Ambassador to Lebanon, Ireland’s Honorary Consul to Lebanon, and the department’s Lebanese lawyer, all of whom attended today’s hearing along with a member of Seán’s family."

He added: "Finally, I appreciate that this is an incredibly difficult day for the family of Private Rooney. None of us can fathom their unimaginable pain and grief, and all my thoughts remain with them at this time."

Additional reporting by Gráinne Ní Aodha.

* This article was originally published on Extra.ie.