Northern Ireland's First Minister Peter Robinson has joined calls for independent monitoring of the IRA and urged the British Government to suspend the Assembly and convene urgent political talks.
The Irish Government has already signalled its support for a new body to investigate the IRA ceasefire, after senior police said the organisation still existed, and warned multi-party talks with London and Dublin overseeing the process could be imminent.
The leader of Northern Ireland's largest party, Mr Robinson met Prime Minister David Cameron tonight after failing in a bid to suspend Stormont to allow dedicated negotiations to take place.
The Democratic Unionist said: "Our concern is that the process requires urgent talks, the Prime Minister and Secretary of State (Theresa Villiers) agreed with that analysis.
"Our view was that those talks should be held in an atmosphere where people were concentrating on those issues and normal business was not proceeding.
"I think that there was a recognition on their part that we had done the right thing by trying to adjourn the Assembly to allow the talks to take place."
Mr Robinson added that decisions need to be made by Monday on how to clear space for talks.
Asked about independent monitoring of the IRA, he said: "I see that as being a small part of the issue of how to deal with paramilitary organisations.
"It is, on its own, not sufficient."
Police Service of Northern Ireland (PSNI) chief constable George Hamilton has said the Provisional IRA still exists and some members were involved in the murder of a father-of-nine last month.
The revelations have shaken the political establishment in Northern Ireland, following Sinn Fein assurances that the IRA had gone away and the assessment of a 2008 British and Irish Government-appointed Independent Monitoring Commission (IMC) report which declared that the IRA has disbanded its terrorist structures and relinquished the leadership necessary to wage war.
Police believe the killing of Kevin McGuigan in East Belfast was a revenge attack by republican associates of IRA commander Gerard "Jock" Davison, who was gunned down in May.
The chief constable said the IRA was not engaged in terrorism - instead pursuing peaceful, political republicanism - and that there is no evidence the McGuigan killing was sanctioned by the IRA leadership.
But the Ulster Unionist Party (UUP) said it could no longer work with Sinn Fein because trust has been shattered and decided to leave powersharing.
Ms Villiers also suggested that bringing back the IMC, which last reported on paramilitary activity in 2011, could restore trust between unionists and republicans.
Dublin's Foreign Affairs Minister Charlie Flanagan said: "I would expect there will be a level of talk and negotiations over the next few weeks."
Earlier, the Democratic Unionists were defeated in a bid for a four-week adjournment of the Northern Ireland Assembly to allow for political negotiations after other parties voted against the proposal.
Stormont's Sinn Fein Deputy First Minister Martin McGuinness said he would be prepared to take part in a new talks process.
"I don't think it was a good idea looking for a suspension of the institutions for a four-week period and I think it would be an even worse idea if David Cameron were to effectively suspend these institutions and return direct rule ministers for whatever time."
Sinn Fein is seeking an urgent meeting with Mr Cameron.
Downing Street said Mr Cameron realised the gravity of the situation and had asked Ms Villiers to hold talks with Northern Irish parties and the Irish government to help secure an agreement.
A spokeswoman said: "The Prime Minister recognised the gravity of the current situation and the need to rebuild trust and confidence in the political process in Northern Ireland. He reiterated his commitment to the devolved institutions and to tackling any remaining paramilitary activity in Northern Ireland.
"The Prime Minister has asked the Secretary of State for Northern Ireland to hold further urgent talks with the political parties in Northern Ireland and the Irish Government with the aim of agreeing a way forward that builds a better future for the people of Northern Ireland."
Lord Trimble, former Ulster Unionist leader who won the Nobel Peace Prize for his peace process work, and current UUP leader Mike Nesbitt have argued that setting up a new IMC would help restore trust in Sinn Fein, which maintains that the IRA does not exist.