The government is "absolutely determined" to see those responsible for the killing of a peacekeeper in Lebanon brought to justice.

Minister for Foreign Affairs Micheál Martin was speaking as he visited Ireland's peacekeeping troops at Camp Shamrock in the country.

The Tánaiste laid a wreath at a memorial to Private Sean Rooney who was killed in a shooting incident in December.

Mr Martin, who was also due to meet the Lebanese ministers for foreign affairs and defence, said he will "impress upon them the need to ensure that the Lebanese investigation is as thorough and complete as possible".

Mr Martin previously visited the base during his term as Taoiseach.

He told peacekeepers the death of Private Rooney, who was from Co Donegal, made returning even more important to him.

"Private Rooney's death was a shocking reminder to all of Ireland of the risks taken by each and every one of you, in discharging your duty and maintaining our country's proud record and reputation," he said.

"I'm conscious that all of you have lost a comrade and a friend. It is to your immense credit that, notwithstanding your personal loss, you have continued to perform with the professionalism we have come to expect from our Defence Forces.

"Nonetheless, I would encourage you to reach out and seek support if you need it, especially when you return home. Support services are available, don't hesitate to use them.

"You have come through a very difficult experience and you need to mind yourselves."

Mr Martin also acknowledged those who were injured in the incident at Al-Aqbiya, particularly Trooper Shane Kearney, who was critically injured.

Tpr Kearney from Killeagh suffered a serious head injury when his convoy came under attack while travelling to Beirut last December.

He returned to Ireland just before Christmas in a specially equipped, contracted medical aircraft.

The young peacekeeper was then taken by ambulance to Beaumont Hospital in Dublin for ongoing medical treatment.

Private Kearney joined the Defence Forces in October 2018, and his home Unit is 1 Cavalry Squadron in Collins Barracks Cork.

He previously served overseas with the 117 Infantry Battalion UNIFIL.

"We are all immensely grateful that Trooper Kearney is now back in Ireland and making good progress with his recovery," he said.

"It goes without saying that we wish him continued progress in the coming weeks and months."

Mr Martin said lines of inquiry are being pursued by the Defence Forces Multi-disciplinary Team into the killing of Private Rooney, as well as three separate parallel investigations into the facts and circumstances of the matter by the Lebanese authorities, United Nations Interim Force in Lebanon (UNIFIL) and Irish police.

"The government is absolutely determined that all of the facts and circumstances of the incident are fully established and that no stone will be left unturned to ensure that those responsible are brought to justice," he said.

He added: "On behalf of the Irish people, may I thank each and every one of you for the part you are playing in continuing the proud tradition of generations of Irish peacekeepers."