Standing together outside Stormont, the prime ministers of Britain and Ireland spoke of their shared horror and determination to continue working together for peace.
Mr Blair said: "I will carry on to my last breath working for peace in Northern Ireland and will carry on doing it because I believe in it, I believe it is possible to achieve.
"We will not let these people wreck the future. The future belongs to the decent people of Northern Ireland."
The two talked for more than hour, in a round of talks aimed at uniting all shades of political opinion against the renegade group and keeping the quest for peace on track.
Mr Blair later met with Northern Ireland First Minister David Trimble at Hillsborough Castle after an unscheduled stop at Belfast's Royal Victoria Hospital. Further meetings are expected today.
The bombing brought an important political milestone in republican terms as Sinn Fein's president, Gerry Adams, explicitly and unequivocally condemned the incident. Sinn Fein has for many years refused to use the word "condemn" in relation to violence.
Mr Adams said: "I reiterate my total condemnation of this action. I have spoken out about the way I feel and those responsible should reflect carefully on that. I want to see this group stop their actions and the political leaders get together."
Republican sources said the reaction throughout their movement was one of "revulsion".
While the implications for the peace process are unclear at this stage, the republican movement has put itself on the same side of the line as the British government and the Ulster Unionists.
An official spokesman for Mr Blair said the terrorists would be given no hiding place amid rising hopes that they will be "shopped" to the police or the Provisional IRA by their own community.
He said: "The change in the political situation should not be overlooked. Overseas or at home, these people have got no friends in high places in any civilised country on earth. They have got no votes, no political support, no great numerical support. They stand for absolutely nothing but terror. They are basically criminals and in some cases psychopaths."
Sinn Fein's Martin McGuinness hinted that the nationalist community will come out against the renegade group, raising hopes that those responsible will be identified. He said: "I think people will make it crystal clear that these people should not be allowed to wreck the peace process."
Mr Ahern said he believed the republican hero Bobby Sands "wouldn't have stood over the horrific events of yesterday" - seen as a pointed reference to the sister of the dead hunger striker who has founded a dissident republican pressure group.
The bombing increased speculation that the split in the IRA could lead to a new and bloody feud.
Andrew Mackay, the Conservative spokesman on Northern Ireland, said he believed the lives of Sinn Fein leaders could be at risk. Calling for the IRA to inform on the breakaway group which carried out the bombing, Mr Mackay said: "Adams and McGuinness could be quite worried for their own safety. If you look at Irish history, when there are splits in the republican movement, they 'do in' the leaders of the mainstream group. I would make sure the security forces get these people [the dissidents] first.
"I believe there is an opportunity here for the mainstream republican Sinn Fein-IRA to end the cancer of terrorism in Northern Ireland by co- operating, because they know who these people are."Reuse content