The report says the IRA army council no longer operates
Northern Ireland's politicians must complete the peace process now the IRA army council no longer operates, Prime Minister Gordon Brown has said.
The Independent Monitoring Commission, which monitors ceasefires, found the IRA's army council serves no function.
"I believe that this will provide reassurance and hope for everybody," said Mr Brown.
First Minister Peter Robinson has said he wants assurances that the IRA army council will never meet again.
The foundations for power-sharing between the DUP and Sinn Fein were laid at the St Andrews political deal of 2006, and identified May of this year as a target date for the transfer of justice powers.
But the DUP has insisted it will not budge until the circumstances are right. Sinn Fein has threatened to pull its ministers out of the Stormont cabinet if progress is not made soon.
Mr Robinson said: "I believe essentially we have this issue to the line but perhaps not yet over the line.
"In my view, for the IMC to say that the army council is not meeting is a different thing to say that it is not in existence.
Gordon Brown said the announcement provided 'reassurance and hope'
"We want a very clear confirmation from the leadership of the republican movement that the IRA is out of business for good." The prime minister said he would work in the next few days to work political parties here.
"In the next few days, I will use all my efforts to make sure that the devolution of policing and justice can go ahead and the final stages of the peace process will now be completed, to the better government of Northern Ireland and to the peace and prosperity of the people there."
Sinn Féin president Gerry Adams said it was clear "the IRA left the stage some time ago".
"So, the issue of the IRA has been dealt with definitively - all concerns have been met (and) this issue is gone," he said.
"We now have to work together to make this partnership government work and to deliver for people on the many bread-and-butter issues that concern them at this time."
Mr Adams said his party would hold talks with the DUP on Thursday "to discuss outstanding issues".
In its report, the Independent Monitoring Commission said the IRA had relinquished the leadership and structures it used during the troubles.
In a report given to the British and Irish governments, the IMC says it does not expect an announcement from the IRA that the army council will disband.
"We are aware of the questions posed about the public disbandment of (Provisional Irish Republican Army's) PIRA's leadership structures," the report said.
"We believe that PIRA has chosen another method of bringing what it describes as its armed struggle to a final close.
"Under PIRA's own rules the army council was the body that directed its military campaign.
By taking these steps PIRA has completely relinquished the leadership and other structures appropriate to a time of armed conflict
"Now that that campaign is well and truly over, the army council by deliberate choice is no longer operational or functional.
"This situation has been brought about by a conscious decision to let it fall into disuse rather than through any other mechanism."
The report concluded: "The mechanism which they have chosen to bring the armed conflict to a complete end has been the standing down of the structures which engaged in the armed campaign and the conscious decision to allow the army council to fall into disuse.
"By taking these steps PIRA has completely relinquished the leadership and other structures appropriate to a time of armed conflict."
Unionists have said political progress is being blocked by the IRA's failure to completely disband.
They are hoping to avoid a major crisis over the future of the power-sharing government and are divided over such issues as the devolution of justice powers, education reform, the future of the Maze prison site and the promotion of the Irish language.
BBC Ireland correspondent Mark Simpson said it is hoped the new report will help ease the current tensions at Stormont, where the power-sharing executive has not met for almost three months.
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