The British Prime Minister, Mr Tony Blair, has said it is still possible to revive the collapsed political process but that it can only happen based on a copper-fastened republican commitment to end paramilitarism and criminality.
Mr Blair said that unionists were "entirely justified" in refusing to share power with Sinn Féin after the PSNI chief constable said the IRA was responsible for the £26.5 million Northern Bank robbery.
But while unionists called on the British government to somehow exclude Sinn Féin from the political process, Mr Blair said it was still possible to achieve a comprehensive political agreement. The onus for progress, however, lay with republicans.
"Unionism has accepted now that it must share power with republicans and nationalists. But it is entirely justified in saying it will not share power unless there is a definitive end to all forms of paramilitary activity or criminal activity by one of the parties that is associated with a paramilitary group," said Mr Blair.
"It can't be 99 per cent giving up violence, and it certainly can't be 80 per cent giving up violence, it has got to be 100 per cent," he told the BBC's Breakfast with Frost programme yesterday.
A senior London source added: "The onus is now on the republican movement. We want to move forward but the message has to be very clear that there is no prospect of progress unless such criminality and paramilitarism completely ends."
Meanwhile, Sinn Féin chairman Mr Mitchel McLaughlin reacted angrily to the Taoiseach's claims that the political leadership of Sinn Féin knew about the planned Northern Bank raid even as it was negotiating the recent failed political deal with the governments.
"This is a direct attack on the integrity of Gerry Adams and Martin McGuinness. Many nationalists and republicans will be deeply disappointed that the Taoiseach has chosen to believe the British and to jump onto the DUP bandwagon of blame.
"That the Taoiseach should do this, after years of working closely with this party's leadership in the peace process, is a grave blow and will be an encouragement to all those, particularly in the DUP, who have consistently sought to attack and undermine the efforts for peace," added Mr McLaughlin.
He said the Sinn Féin commitment to the peace process had been "the dynamic sustaining the process and moving it forward". Sinn Féin would not be deflected from this, but the task was "made more difficult when the governments attack our leadership in this way", Mr McLaughlin said.
DUP deputy leader Mr Peter Robinson and other unionists over the weekend said that the SDLP now had a "moral responsibility" to join with the DUP and Ulster Unionists in an Executive and to see Sinn Féin excluded from the administration.
SDLP leader Mr Mark Durkan, while accepting that the IRA carried out the Northern Bank raid, rejected these overtures.
"Sinn Féin last week called on everyone to move on without the DUP. The DUP this week is calling for everyone to move on without Sinn Féin. The SDLP isn't going to follow any of these parties. We're going to stand as we always have done, for the Good Friday agreement, and for getting it fully implemented despite the obstacles that Sinn Féin, the IRA and the DUP have put in its way," he said.
Mr Durkan said that while "the IRA has got itself millions of pounds they also have almost bankrupted the chances of the people of Ireland getting all of the agreement".