The Taoiseach said yesterday that the Northern Ireland talks could continue without Sinn Fein, but Mr Ahern refused to commit himself on whether the party should be expelled from the process.
Meanwhile, the Fine Gael leader, Mr John Bruton, said the two governments had to make a judgment, not on the forensic evidence on a particular weapon, "but on the long-term political intentions of the republican leadership".
Mr Ahern, who was in Cork, said the peace process guidelines governed all participants and Sinn Fein was no exception. On Monday, there would be discussions between all sides. After that, Sinn Fein's role in the talks would be determined.
The discussions would decide who should remain and who should leave the talks process, but "I can't call the outcome", Mr Ahern added.
He said he did not believe the peace process was doomed. Asked if there could be any peace process without Sinn Fein, he said, whatever happened after Monday's discussions the talks would continue. He believed the process would work. Mr Ahern denied that this suggested Sinn Fein might be expelled from the talks for a period and then invited back.
The Taoiseach said he had spoken about the new situation to President Clinton and to the British Prime Minister, Mr Tony Blair, on Thursday. He refused to comment on reports that the Chief Constable of the RUC, Mr Ronnie Flanagan, had indicated that the IRA had been involved in two recent killings in the North, adding that while the situation was critical, Sinn Fein's continued participation was a matter yet to be discussed.
Mr Bruton suggested the governments were right to take a firm approach to the application of the Mitchell Principles to all parties, without discrimination.
The Hume-Adams process, the Forum for Peace and Reconciliation and the all-party talks were part of a process to educate the republican movement on the limits to what could be achieved by communities on the island of Ireland, Mr Bruton said.
"At each stage of the process where the republican movement met an unpalatable limit which contradicted its unchanged fundamentalist ideology, it reverted to what it knew best," he said.
The Labour leader, Mr Ruairi Quinn, said Mr Flanagan's announcement gave cause for serious concern. Clearly, Sinn Fein was wanted at the talks, but the rules applying to other parties should also apply to it.
If and when evidence was produced linking the Provisional IRA to these murders, the governments would have to consider removing Sinn Fein from the talks.
"The only way the expulsion of Sinn Fein can be avoided, if such evidence is produced, is if the political leadership of Sinn Fein, who I believe remain committed to the talks process, dissociate themselves from these two recent murders," Mr Quinn said.
If Sinn Fein could not meet this test, then the decision would have been taken out of the governments' hands.