The Ulster Unionist Party leader, Mr David Trimble, has warned he will take action by the end of July, if the IRA does not clearly demonstrate it is totally committed to peaceful means of advancing its objectives.
He issued his warning after a summit at Hillsborough of the British and Irish governments and the pro-Belfast Agreement parties yesterday.
Mr Trimble said a serious problem would confront the two governments and the parties if the IRA did not refrain from violence.
He called on the British Prime Minister, Mr Tony Blair, to censure Sinn Féin if there was further evidence of the IRA engaging in violence.
"If we don't see significant progress by government in the course of this month before parliament goes into recess then, in the absence of clear actual movement by government within that time-scale, we feel there is going to a very serious problem indeed," said Mr Trimble.
He refused to specify what action he might take but intimated that it would involve some form of sanctions, either through demanding Sinn Féin ministers be expelled or through UUP ministers withdrawing from the executive. "You can pretty well work out what the extent of that problem will be. I myself don't want to spell out the obvious because then it will look as if we are making threats," said Mr Trimble.
The Taoiseach, Mr Ahern, and Mr Blair engaged in an afternoon and evening of bilateral talks with the pro-agreement parties. They had an hour of talks with Mr Trimble, who then left Hillsborough refusing to participate in a subsequent round-table meeting with the two leaders and the parties.
The main focus of the summit was to help restore unionist confidence in the Belfast Agreement and bolster Mr Trimble's leadership of the UUP.
Mr Blair said there was a unionist perception that the broad republican movement could engage in politics while at the same time engaging in violence.
"That is not acceptable," said Mr Blair.
"Transition means full transition from violence to democracy. Now we have got therefore to look at the ways we make that clear, that we lay down the clear principles that we have to abide by, and what happens if people don't abide by them. That's what we have to reflect upon," he added.
Mr Ahern said he did not interpret those remarks as the prime minister threatening sanctions against Sinn Féin. He wanted to see a move from a society "that had paramilitary activity, that had a paramilitary element to it, to one of total democracy. Neither of us wants to see that taking too long. We want to see it happen sooner rather than later."
The Sinn Féin president, Mr Gerry Adams, said there could be no sanctions against Sinn Féin, which had a democratic mandate from its electorate."No sanctions can be taken under the terms of the Good Friday agreement against those people who vote for us, or against any other section of the electorate," Mr Adams said.
He pledged that the republicans would do their utmost to defuse community tensions and help restore broad confidence in the agreement. "The issue of armed groups has to be tackled. How do we do that? By coming together, not just at crisis meetings or summits but day in day out by setting an example, by implementing the agreement."