Sinn Féin president Gerry Adams has apologised to the parents of a 12-year-old boy killed in an IRA bomb attack in 1993.
Mr Adams paid tribute to Colin and Wendy Parry, whose son Tim died along with three-year-old Johnathan Ball in the Warrington bomb.
As he took part in a debate on paths to peace in London's Canary Wharf alongside Colin Parry, the West Belfast MP apologised for the hurt inflicted by the Provisional IRA during Northern Ireland's Troubles.
"The Tim Parry/Johnathan Ball Foundation for Peace is an optimistic example of how people, who have been grievously hurt, are able to meet that challenge head on and to produce something good and constructive, and positive and compassionate, from it," he said.
"I therefore want to acknowledge Colin and Wendy Parry's personal journey and how they have created this positive space from the place of deep trauma and grief they personally experienced.
"Irish republicans - the IRA - was responsible for what happened that day. It brought huge grief to these two families, as well as to others hurt in that incident.
"The IRA expressed its regret at what had happened. In 2002 it apologised to all those non-combatants it had killed or injured and their families.
"I have also expressed my personal and sincere regret, and apologised for the hurt inflicted by republicans. I do so again this evening. This is the right and proper thing to do."
Tim Parry and Johnathan Ball were killed by bombs concealed in litter bins close to a busy shopping centre in Warrington in March 1993.
Colin and Wendy Parry set up a foundation to encourage reconciliation in Northern Ireland with the support of Wilf and Marie Ball, Johnathan's parents.
Prior to tonight's debate, Mr Parry acknowledged it would be difficult for him to share a platform with Mr Adams.
"Meeting Mr Adams and sharing a public platform with him will be very challenging for me," he said. "However it is a vital step on my own personal journey to reconciliation and a vital step too for the foundation in living up to its charter principles."
In 1996, Canary Wharf was the scene of a bomb attack which killed two people and marked an end to the Provisional IRA's two-year ceasefire.
Mr Adams also said United Nations officials could chair an independent truth commission investigating killings carried out during the Troubles. Mr Adams said a truth process should involve all people, including those in England and the Republic, bereaved or maimed during the Troubles.
"A truth process must reach out to these people," he argued. "One way of achieving an independent process is to have an international inquiry. The United Nations or another reputable agency could be involved.
"In Ireland many of the victims groups are looking at this proposition for an Independent International Truth Commission and I have met them on this. I think there is merit in this idea."