Sinn Féin has ruled out the prospect of republicans co-operating with the Independent Commission to monitor paramilitary ceasefires and political progress in the North.
The party argued that the commission was being set up outside the terms of the Belfast Agreement as a concession to anti-agreement unionists.
Its president, Mr Gerry Adams, said the commission was "impractical", but said republicans "don't have any problem with political parties or indeed with anyone being held to account".
Mr Adams was speaking in Dublin after he and the Sinn Féin chief negotiator, Mr Martin McGuinness, met the Taoiseach, Mr Ahern, yesterday morning.
He said afterwards that they understood Mr Ahern would continue to urge his British counterpart, Mr Tony Blair, to set a date for power-sharing elections.
"In a very short time these institutions will have been suspended for a year. You just can't sustain it," Mr Adams said. Parties had made strenuous efforts to ensure that the summer period was largely peaceful, he said.
The setting of a date in the autumn for an election, postponed in May, was now the most crucial political issue.
"We're satisfied that the Taoiseach is at one with us on the need and the imperative of an election," Mr Adams said.
But when asked whether Mr Ahern could be satisfied that republicans are going to co-operate with the monitoring body, Mr Adams said: "No. Why should we? We're against it. Why should we co-operate with something we're against?"
He said the party had made its view clear that the commission was "impractical" and outside the terms of the agreement.
"We do have a problem with the fact that this monitoring group is clearly being put together, was conceived to placate unionism and then since it was first put forward has been tinkered with, diluted and messed about with to meet the needs of factions within unionism."
Mr McGuinness said the establishment of the commission would fundamentally change the nature of the agreement.
"We don't have any difficulty whatsoever with people being held accountable or of the situation on the ground in the North being monitored," he said.
"But we do have a difficulty with fundamental changes to what was an international agreement and the fact that we as a political party in the course of the referendum into that agreement brought our considerable vote to bear in the island of Ireland to support that agreement."
Mr McGuinness added: "I hope the British government reflects on the situation that has existed over the course of recent weeks and months and that the British prime minister will accept the Taoiseach's arguments that he should go for the election in the autumn of this year."
