Ulster Unionist leader Mr David Trimble was today accused of trying to dupe his supporters about his involvement in a package aimed at securing moves from the IRA on paramilitary activity.
Democratic Unionist deputy leader Mr Peter Robinson accused his rival of trying to pull off "a sleight of hand" by pretending to distance himself from whatever package might emerge next month in talks involving the Taoiseach and British Prime Minister Tony Blair.
The east Belfast MP said: "We could very well witness again a sleight of hand from the Ulster Unionists where they will privately give a nod and a wink to a whole raft of concessions to nationalists and republicans and then huff and puff publicly when it is produced".
Mr Blair and Mr Ahern and their officials are piecing together proposals for their talks in Downing Street on Thursday. They will then travel to Hillsborough for talks next Monday.
The British government has been pressing for a comprehensive statement from the IRA on future paramilitary activity. The IRA is also being asked to carry out a verifiable act of decommissioning and to outline a process for emptying its arms dumps over a three-year period.
But republicans have insisted an implementation plan for the Belfast Agreement is needed if the IRA is to respond and Sinn Féin is also to publicly endorse policing and take its seats on the province's Policing Board.
London and Dublin officials are reported to have been working on an offer to scale down military installations over three years and have been contemplating the withdrawal of thousands of troops within a few weeks as well as the dismantling of dozens of watchtowers along the border with the Republic.
Mr Robinson said the current speculation about radical demilitarisation proposals from the Government and an amnesty were "an outrage".
"Unionists will not be encouraged to support the Belfast Agreement on the basis of these nor will they feel secure by the removal of troops on the scale that is being floated in press reports," he said.