The Irish and British governments have denied reports that Mr Tony Blair and the Taoiseach will propose a six-month transitional executive when they meet the Northern political parties at Downing Street on Thursday.
The parties are to meet in a further attempt to break the decommissioning deadlock as speculation continues that the process may be "parked" over the summer without agreement soon.
The reports of a plan involving a transitional executive are understood to reflect the content of some proposals which have emerged since the Hillsborough Declaration in efforts to overcome the impasse.
But a Government spokesman said last night that no such proposal would be made by the two governments this week.
"A number of proposals are being examined and that isn't one of them," the spokesman said. There were many ideas in circulation, he said, but "no proposal of that nature is being pushed by us".
Reports circulating yesterday said Mr Blair and Mr Ahern would make a last effort on decommissioning by proposing such a transitional six-month shadow executive.
Sinn Fein would be entitled to take up shadow ministerial posts prior to decommissioning, according to this report.
During the interim period, pressure would be applied to Sinn Fein to deliver some IRA decommissioning while both leaders, the reports said, would guarantee full powers would not be transferred to Stormont until some weapons were handed over.
According to the reports, shadow ministers and Assembly committees would work alongside civil servants to devise future work programmes in preparations for the full transfer of powers.
But Downing Street echoed the Government's denial of the plan, saying the plan "didn't come from us" and insisted any plans put to the parties on Thursday would not be published beforehand.
The Ulster Unionist negotiator, Sir Reg Empey, said such a proposal had not been put to his party and he did not wish to comment. Mr Mark Durkan of the SDLP also declined to comment specifically on any plan until the Taoiseach and the Prime Minister had actually put it to the parties.
However, he said it appeared to be a variation on ideas suggested in previous discussions. "It's not a matter of the two prime ministers proposing something as we learned at Hillsborough. What we need is for the parties to agree the basis of the next steps.
"This is not going to be solved without Sinn Fein and the Ulster Unionists. We need to be moving towards implementation of the institutional aspects of the agreement.
"The SDLP hopes that sort of development can also assist progress in the disarmament area."
Mr Ian Paisley jnr of the DUP said any proposal that delayed dealing with decommissioning was "just kidding people". He said: "Transitional executive or full-blown executive, it makes no difference."
"Sinn Fein would have the status and practically the powers of ministers without a single weapon handed over by the IRA.
"David Trimble has already put off the decommissioning issue from July 1996 and the SDLP would put it off until May 2000. It can't be put off again."
The Sinn Fein Assembly member Mr Gerry Kelly said he would reject any form of "genetically modified" Hillsborough declaration which made his party's seats in government dependent on an IRA arms handover.
Mr Kelly said no such proposal had been put to Sinn Fein but he rejected the idea as "moving away from the Good Friday Agreement".
"The power to move the process forward is in the hands of the British government, which should call the democratic bluff by triggering formation of an executive immediately."