The Ulster Unionist party leader David Trimble has said the IRA must decommission if the Northern Assembly is to be restored.
Speaking at his party's annual conference where he was re-elected as leader, Mr Trimble made his demands amid reports the IRA is preparing to make a significant gesture to help restore the suspended power-sharing executive.
Mr Trimble said he would not consider returning to government with Sinn Féin unless the IRA decommissioned and said the war was over.
He said republicans must act to restore confidence in the power-sharing executive at Stormont. "We want the Assembly back but it will not happen unless Republicans act," he said adding, "The onus is on them. They know what has to be done. The time for talk is drawing to an end."
He said "Without Republicans changing, acknowledging that they got it so dreadfully wrong, making amends, indeed if not words, the future is bleak.
"We have tried, tried and tried again to wean Republicans from violence.
"If we fail again the world will know that Republicans, not Unionists have blocked the path to peace, blighted hopes for the future, frustrated the agreement."
Mr Trimble's comments come ahead of Monday's summit meeting with the pro-agreement parties in Belfast to be hosted by the British Prime Minister, Mr Tony Blair, and the Taoiseach, Mr Ahern.