The return of the Northern Ireland Assembly and Executive will require progress on policing and the removal of British army posts and not just the end of paramilitary attacks, the Taoiseach has indicated.
Speaking in Dublin, Mr Ahern said: "We want to try and get resolution to all issues in our view. Solving one of them will not put this back together again."
Since the weekend, senior Government officials have been planning a meeting of the British/Irish Inter-Governmental Conference "perhaps within the next 10 days", sources said last night.
There is concern that the meeting involving the Taoiseach and the British Prime Minister, Mr Tony Blair, should not become "just a talking shop", but offer a route map for the way ahead.
During talks in Dublin last week, he said the SDLP, Sinn Féin and the Ulster Unionists had all said they wanted and "indeed preferred" to have the institutions "back up and running" before May.
Shying away from talk of joint authority, Mr Ahern said: "My only concern is to build back the institutions back up again. We don't want any more role than that."
Despite allegations that a Provisional IRA crime was foiled in Bray last Friday, Mr Ahern said the Garda Síochána and others had advised him that the Provisionals pose "no threat to the ceasefire".
But the first IRA ceasefire dates back to 1994. "It must be made clear that the transition from violence to exclusively peaceful means has been brought to an unambiguous and definitive conclusion," he said.
Urging all Northern parties to help end the current crisis, he said that "it is always dangerous to leave a political vacuum". "The Irish and British governments must move on apace. Otherwise it would be very dangerous." Outlining the key areas, Mr Ahern said the legislation implementing policing changes agreed during the Weston Park talks last year must be passed by the House of Commons.
On demilitarisation, he said: "Nationalists feel that they are seeing far too much security. They feel that there is peace, and they are playing their part. We should see huge implementation of demilitarisation policy."
Meanwhile, the Tánaiste, Ms Harney, said Northern political and community leaders must now rebuild the trust and confidence necessary to end the suspension of the institutions.
She echoed the remarks made by the Northern Secretary, Dr John Reid, who said the time has now come for all those involved to make a final choice between violence and democracy.
She went on: "I firmly believe the desire amongst the majority of ordinary people on either side of the political divide is for the full implementation of the agreement."