The Good Friday Agreement would not have been achieved without the backing of prisoners on both sides, a former Methodist president has said.
Rev Harold Good was speaking in Bilbao in Spain at the weekend, at a ceremony marking the first anniversary of the disarmament by the militant Basque separatist group ETA.
Rev Good and the late Fr Alec Reid oversaw the decommissioning of the Provisional IRA weapons and were also involved in the moves to bring about ETA decommissioning.
He told the Bilbao audience: "We discovered in Northern Ireland that by removing the visible and tangible threat to peace, decommissioning provides the opportunity to begin the search for a lasting peace.
"That is why I emphasise that disarmament is a beginning and not an end."
Rev Good said there was a difference between peace-making, which is the beginning of a new journey, and peace-building which is the continuation of that journey. "Having played a significant role in the making of a peace which allowed for their early release, it was the responsibility of ex-prisoners to play their part in the building of a sustainable peace."
He said that in Northern Ireland "it was only after many years of dismissal and protest, including hunger-strike deaths, that the term 'politically motivated' was accepted, with reluctance".
"But this was a major step forward, as it allowed for the inclusion of politically motivated prisoners in the search for a resolution to our long-running and bloody conflict."
Rev Good added however: "In saying this, it is important for me to emphasise that this in no way legitimises or endorses the activities of either republican or loyalist paramilitaries. Their respective campaigns of terror brought unspeakable grief upon our relatively small community.
"This cannot be forgotten by the victims and survivors most personally affected.
"So in this week, during which we will be marking the 20th anniversary of the Good Friday Agreement - and you are marking the first anniversary of the decommissioning of ETA weaponry - we reflect upon the clear message from the history of Ireland, that without the engagement and inclusion of all prisoners' groups, there would have been no Agreement."
The ETA group, which sought independence in the Basque region, killed over 800 people in a 40-year campaign of violence.
It declared a ceasefire in 2011, but formally disarmed only last year at a ceremony in the French city of Bayonne.