Former minister of state and key Fianna Fáil adviser Martin Mansergh has died aged 78.
Mr Mansergh was elected as a senator from 2002 to 2007 and as a TD for Tipperary South from 2007 to 2011.
He served as minister for state with responsibility for the Office of Public Works.
Mr Mansergh was also an adviser to leaders of Fianna Fáil during the peace process in Northern Ireland.
He died on a trip to the Sahara with other retired parliamentarians.
President Michael D Higgins leads tributes
President Michael D Higgins has paid tribute to Mr Mansergh, acknowledging his "significant contribution" to the peace process.
"It is with sadness that so many will have learned of the death of Dr Martin Mansergh," he said in a statement.
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"Dr Mansergh earned the respect not just of people with different interpretations of the historic events which led to Irish independence, but of colleague historians for the sophisticated presentation he offered on what were often complex and contentious issues.
"Dr Mansergh's capacity for detail was of enormous assistance in the period leading up to the Good Friday Agreement and in the very significant contribution which he made to the broader peace process."
"His advice to politicians, and to the different Taoisigh which he served, and later as a member of the Oireachtas where he represented Tipperary, was always to begin with the facts."
The President continued: "Among his colleagues in Leinster House, he was deeply appreciated for his deep courtesy, but also for his sense of humour.
May I express my deepest sympathies to Martin's wife Elizabeth, to his children and extended family, to his former colleagues, and to all of his many friends."
Taoiseach Micheál Martin said he learned of Mr Mansergh's death "with great sadness".
Paying tribute to him, Mr Martin said his contribution in "securing peace on this island mark him as a figure who will always be honoured".
"His early, secret negotiations in Belfast on behalf of Taoisigh and his work through more than a decade were essential in securing the peace settlement and the overcoming of later hurdles," Mr Martin said.
"As a diplomat and then as an advisor to leaders of Fianna Fáil both in government and in opposition, he was exceptional in his knowledge and devotion to the cause of peace on our island and throughout Europe," Mr Martin said.
"Martin was a one-off. A true Irish republican. A man of great accomplishments who leaves a proud history," he added.
Adams and Ahern pay tribute to Mansergh
Former taoiseach Bertie Ahern said Mr Mansergh was "an extraordinary person with a towering intellect with the ability to see so many angles of a problem or equally an opportunity".
"He gave his life to public service starting in the Department of Foreign Affairs and then went on to serve Charles Haughey and then Albert Reynolds and finally myself in our roles as Taoiseach and leaders of Fianna Fáil.
"Today I'm thinking of his wife Liz and his family who will be mourning the loss of a great and gentle man and person who made a huge contribution to peace on the island of Ireland," Mr Ahern added.
Former Sinn Féin leader Gerry Adams also paid tribute to Mr Mansergh.
"Martin Mansergh was a key figure in the efforts to build the peace process and the success of the negotiation leading to the Good Friday Agreement.
"He was one of those who met with Sinn Féin in the late 1980s on behalf of Fianna Fáil and we retained a close relationship since then," Mr Adams said.
"Martin served a number of Taoisigh and his crucial role, along with other senior government officials, and John Hume, and Sinn Féin representatives, was in the build up to the negotiations at Good Friday in 1998 and in the work that was done after that.
"I value very much the numerous engagements that we had and the relationship that we developed as a result of that.
"I wish to extend my sincere condolences to his wife Elizabeth and his five children," he added.
Mansergh 'a person of great integrity' - Harris
Tánaiste Simon Harris said Martin Mansergh was a person of great integrity, saying fewer people were "as consequential in shaping Irish Government policy on Northern Ireland".
He added that "few on the Irish side were more crucial to the Peace Process, whether through his role as an intermediary or his work to craft a new political and intellectual framework for peace".
"On a personal level I knew Martin to be a warm, generous with his time and insights, and a person of great integrity with incredible commitment to peace on our island," he added.
Sinn Féin leader Mary Lou McDonald said Mr Mansergh "played a key role" in peace negotiations.
"It was with deep sadness that I learned of the passing of Martin Mansergh. He was deeply committed to public service as an elected representative, diplomat and advisor to a number of Taoisigh," she said.
He played a key role in the early days of the peace process and throughout the negotiations leading up to the Good Friday Agreement, working with Gerry Adams, John Hume and many others.
"A proud Tipperary man, he will be missed by all those who knew him. I extend my deep condolences to his wife Elizabeth and family and to his colleagues in Fianna Fáil."
Northern Ireland's First Minister, Sinn Féin's Michelle O'Neill, also paid tribute to Mr Mansergh, and extended her condolences to his family and colleagues in Fianna Fáil.
I am deeply saddened to learn of the death of Martin Mansergh.
— Michelle O'Neill (@moneillsf) September 26, 2025
Martin played a key role, particularly in the early stages of the Irish peace process and in the later development of the Good Friday Agreement.
I extend my heartfelt sympathy to his family, friends and his…
