Mohammad Ayyad was the main defendant in the proceedings, though a number of other men have also been convicted and received lighter sentences.

Taoiseach Michéal Martin said: “While I welcome the conviction of the main defendant, it is unsatisfactory that he is still at large.

“Many will feel the sentences passed down on the other defendants are far too lenient.

“The justice system in Lebanon, and the delay in progressing in this case, was deeply regrettable.

“Peacekeeping is the most noble cause of all, and the role of the peacekeeper must at all times be honoured and respected.”

He added: “This is a very difficult day for the family of Seán Rooney, in particular his mother Natasha.

“Sean was a soldier of great courage, who put the safety of others before his own safety in the line of duty.

“He was brave and diligent. My thoughts and prayers are with Natasha, his family, friends and colleagues at this difficult time.”