Sinn Féin national chairman Mr Mitchel McLaughlin said his party remained committed to the Northern Ireland peace process and will not be deflected by allegations that the IRA was responsible for the Belfast bank robbery.
Mr McLaughlin said there was deep anger among republicans at politically motivated attempts to criminalise the movement during an emergency meeting of the party's executive in Dublin.
PSNI Chief Constable Hugh Orde told members of the Northern Ireland Policing Board yesterday that he believed the Provisional IRA was responsible for stealing £26.5 million in the Northern Bank raid before Christmas. His statement led unionists to call on the British government to exclude Sinn Fein and press ahead with efforts to restore devolution without them.
But Mr McLaughlin claimed the process had been in difficulty since the Reverend Ian Paisley's Democratic Unionist Party refused to sign up to a deal in December and had merely been worsened by Mr Orde's statement.
"There is no doubt that there are those within the Northern Ireland Office who are seeking to exploit this difficulty to bring about the exclusion of Sinn Fein and ensure that the comprehensive deal will not be achieved," he said.
"The IRA has made clear that it did not carry out this robbery.
"Hugh Orde went to the media yesterday, not on the basis of facts or evidence, but on the basis of reports from securocrats who have been working to undermine the peace process for years now.
"The governments know how much was achieved before Christmas and that the priority must be to get the comprehensive deal across the line."
Northern Ireland Secretary Mr Paul Murphy is due to make a statement to parliament next week, when there will also be a debate on power-sharing in the North.
But both the British and Irish governments have admitted this latest controversy is a massive body blow to efforts to revive devolution.
Mr Murphy has conceded that there was virtually no chance of a return of power-sharing in the next six months. "It is very difficult to see where we go in the immediate future," he said.
The Taoiseach, Mr Ahern described Mr Orde's finding as a "serious setback" and said republicans would have to bring involvement in paramilitary and criminal activity to a definitive end.
The DUP is due to meet the British Prime Minister Mr Blair next week when it will call on the government to form a devolved administration without republicans.
PA