There was an angry reaction in the Dail to the news that the IRA had broken off contact with the de Chastelain commission on decommissioning.

The Taoiseach was midway through his prepared script, during a series of statements on the North, when he was handed a note informing him of the IRA move. He then told the House of the development.

The Fine Gael leader, Mr John Bruton, said: "I believe the IRA has set out, in a calculated way, to humiliate our Taoiseach, the elected leader of the Irish people, and that is not acceptable. How could they allow the Taoiseach, who has acted in good faith in this matter, in good faith with Sinn Fein and all the parties, who has worked all the hours that God sends to bring peace . . . how could they allow a situation to arise where they must have known that the IRA was about to make this decision . . .?

"They allowed the Taoiseach come into the House, and be placed in a position where he was handed a note telling him that the entire basis upon which he was speaking in the House had been taken from under him?"

Mr Bruton praised the Taoiseach for conducting himself very well "in the face of the utmost provocation". He asked how Sinn Fein could have allowed Mr Ahern to speak before the Dail without first telling him the IRA was about to make its decision to withdraw from the decommissioning body.

"They allowed the Taoiseach to come into the House and be placed in the position where he was handed a note telling him that the entire basis upon which he was speaking in this House had been taken away from under him by a secret organisation which is accountable to nobody, elected by nobody, and has no right to act on behalf of the Irish people.

"I think it is the height of impertinence and I'll complement the Taoiseach on the calm and dignified way in which he dealt with this appalling way in which he has been treated by Sinn Fein and the IRA."

Mr Bruton added: "I don't accept the fiction that these are two entirely separate organisations. I know, and the Taoiseach knows, that that's just not true . . . They are indivisible organisations, Sinn Fein and the IRA." Yet Sinn Fein had spoken to the Minister for Foreign Affairs, Mr Cowen, in recent days and "no doubt they didn't breathe a word of this to him. What way was that to treat a new Minister for Foreign Affairs?"

Mr Bruton noted the announcement came the day before the Taoiseach was due to meet the British Prime Minister, Mr Blair.

"What does that suggest? That they didn't want the problem resolved," said Mr Bruton.

"It appears clearly to me that the only motivation possible for sabotaging an imminent effort by the Taoiseach with reasonable prospect of success of having the institutions re-established, that the only reason for this particular timing, was to ensure that it didn't get success because success would embarrass them, because they would have to do something then and they just don't want to. Pride is too great on the part of this movement. They put their own pride before all else. Losing face is more important than making peace."

The Labour leader, Mr Ruairi Quinn, said: "I would like to add my words of deep disappointment and regret that the IRA has so precipitately responded to an action which none of us wanted to see happen, namely the suspension of the institutions in Northern Ireland, but which we, nevertheless, saw as perhaps being the inevitable consequence of a failure by some participants to the process to meet what was understood by others to be their obligations within a given timeframe."

Responding to the Opposition leaders, Mr Ahern said: "Unfortunately, it was out that I was to speak at five o'clock. Obviously, the statement was designed for that. It says it for itself . . . There is no need for me to say any more."

Mr Ahern thanked the Opposition leaders, and all members of the House, for their support, adding: "I suppose the advice that is to be given to us is that when we go out of here, we just get back on with it again. That is the best way."

Earlier, before receiving news of the IRA's decision, Mr Ahern told the House it was a great disappointment for him to have to speak in such circumstances. "Our disappointment is all the greater because the rich potential of the Good Friday agreement has, since the establishment of the institutions in December, begun to translate itself into full reality. And few would have anticipated just how quickly and how significantly the institutions would begin to make their mark."

Suspension of the agreement was a very serious setback, and the Government had done all it could to seek to avert it, he added. "We now need to dedicate ourselves not to apportioning blame, because recrimination simply makes our task more difficult, but to ensuring the earliest possible restoration of the institutions so that the progress we have all welcomed can be built upon and developed."

Mr Ahern referred to the February 11th de Chastelain report on decommissioning, adding that the commission was saying, in effect, that it believed it had a commitment from the IRA, for the first time, that decommissioning would happen. "This is, beyond doubt, a huge advance and progress which we should build upon as quickly as possible. I am glad that the British government has also recognised the significance of this statement, as have the political parties."

Mr Quinn said decommissioning was a central component of the agreement. "It has been supported by public opinion in countless opinion polls ever since, including among Sinn Fein supporters. It is not about surrender or humiliation, it is about building trust between all the peoples on this island."

He said republicans had argued trenchantly for the repeal of the Government of Ireland Act and had got it. "But the IRA must accept, too, the implications of that advance. The people, not Westminster, are now sovereign and change can only come about if they are persuaded that they, the people, want it."