PSNI chief asked to attend cross-party Executive crisis talks
Northern Ireland's most senior police officer could be summoned before talks aimed at saving the region's crisis-hit political institutions.
If the cross-party negotiations fail, it could be a decade before devolved power-sharing in Belfast is restored, First Minister Peter Robinson said.
The warning came as the Ulster Unionist Party (UUP) announced it would withdraw from discussions unless the status of the IRA was resolved.
Mr Robinson said: "If the Assembly and Executive falls we are probably talking about the best part of a decade before it would ever be revived. These are extremely important talks."
The ministerial Executive at Stormont has been under threat of collapse since police confirmed the IRA was still in existence and that individual members were involved in the murder of a man in Belfast last month.
Crunch talks, scheduled to last for four to six weeks, were convened by the British and Irish governments at Stormont House following the police revelations which rocked the political establishment.
Mr Robinson added: "The request that was put today to the government for the chief constable to come to the talks process was made by the DUP. We will be there to hear him.
"The issues that have to be dealt with all have to be dealt with before anything is agreed by us. If the issue of the paramilitary involvement is not resolved, then there will be no overall agreement."
The Police Service of Northern Ireland (PSNI) believe individual members of the Provisional IRA shot Kevin McGuigan dead in revenge for the death of prominent republican Gerard "Jock" Davison in May.
Chief Constable George Hamilton has insisted the IRA is not back on a war footing but exists to pursue a peaceful political republican agenda.
On Monday, the Democratic Unionist Party (DUP), Northern Ireland's largest party, said there would be no further routine meetings of the ministerial Executive until the latest crisis was resolved.
The Ulster Unionist Party has withdrawn its only Executive minister Danny Kennedy, claiming it could no longer trust republicans.
Leader Mike Nesbitt said they could not discuss the Stormont House Agreement, which tackled outstanding peace process issues, until the issue of paramilitarism had been resolved.
After the negotiations, he said: "This is the issue and the only issue that we will speak on. We will consider going into the session which deals with the IRA."
He later added: "We took a principled stand to withdraw from the Northern Ireland Executive on the issue of Sinn Fein's lack of credibility.
"On that basis, we will remain consistent and not participate in political talks unless and until this matter is resolved."
Sinn Fein has accused the UUP of pulling a political stunt for electoral gain.
Newry and Armagh MLA Conor Murphy said: "It's clear, however, from the off that UUP leader Mike Nesbitt is interested only in stunt politics in his electoral contest with the DUP.
"Already his roadmap forward has turned into a cul-de-sac at the first twist in the road as after excluding his party from government he has now excluded them from tomorrow's talks."
Unionists had pressed for measures including a temporary suspension of the Assembly to allow space for negotiations.
But, outlining the British Government's position in a speech to the House of Commons, Northern Ireland Secretary Theresa Villiers said the time was not right for direct rule.
In a statement released after the opening round of talks, Ms Villiers described the tone of the meeting as "genuinely constructive".
She said: "All participants acknowledged that it was vital to resolve the issues on the agenda. The institutions are at risk if this process fails. Northern Ireland's political leaders have achieved great things working together in the past.
"I hope this process will deliver real progress on implementing the Stormont House Agreement and dealing with issues around paramilitaries, to help build a brighter more secure future for Northern Ireland."