The Ulster Unionists have announced their intent to resign from the North’s power-sharing executive and form an opposition over claims the Provisional IRA still exists.
The UUP leader, Mike Nesbitt, has said he is recommending the party withdraw from the power-sharing government.
The UUP's executive is to meet on Saturday to endorse the party leadership's decision. If successful, the party will withdraw from government and form an opposition.
The move comes in the wake of an assessment by the Police Service of Northern Ireland (PSNI) that structures of the supposedly defunct paramilitary organisation are still operating, and some of its members were involved in the murder of Belfast father-of-nine Kevin McGuigan two weeks ago.
Mr Nesbitt said "on a matter of principle" his party would not share power with Sinn Féin if the PIRA still existed.
While the move by the UUP, a minor partner in the five-party mandatory coalition, will not automatically trigger the collapse of the administration, it does throw its future into serious doubt, as pressure will now mount on the North’s largest party, the Democratic Unionists, to follow suit.
Party leader Mike Nesbitt said: “That decision is to withdraw from the Northern Ireland Executive, to form an Opposition and offer people an alternative, as is the way in any proper democracy.
“We are in a bad place but this can be fixed.
“But the IRA need to go away and stop terrorising their own communities.”
Sinn Féin Deputy First Minister Martin McGuinness has accused the UUP of playing party politics.
This decision by the UUP is more about inter Unionist rivalry than their & others feigned concern about our unequivocal commitment to #Peace— Martin McGuinness (@M_McGuinness_SF) August 26, 2015
He said on Twitter: “This decision by the UUP is more about inter Unionist rivalry than their & others feigned concern about our unequivocal commitment to #Peace.”
PSNI chief constable George Hamilton has said that the IRA still exists but is not engaged in terrorism, instead pursuing peaceful, political republicanism.
However, the PSNI also said some of its members were involved in the murder of father-of-nine Kevin McGuigan in Belfast two weeks ago in cooperation with others – but it was not sanctioned at a senior level.
Ireland’s Justice Minister Frances Fitzgerald has ordered a “fresh assessment” of the activities of the Provisional IRA by Irish police.
The PSNI analysis – almost 20 years after the Provisional IRA’s last ceasefire and a decade on from decommissioning its weapons – has triggered another political controversy at Stormont.
There is nothing more Sinn Féin can do - Adams http://t.co/S4uzzEk6Mu— Gerry Adams (@GerryAdamsSF) August 26, 2015
Sinn Féin leader Gerry Adams said the IRA has gone away.
But Mr Nesbitt said the republican party’s position was threadbare and threatened the 1998 Good Friday Agreement which largely ended the conflict and established powersharing.
He added: “The Single Transferable speech denial (by Mr Adams) totally lacks credibility. It has shattered trust.”
The Irish and British Governments appointed an Independent Monitoring Commission (IMC) to verify arms decommissioning by republicans and loyalists.
In 2008 it said the IRA had disbanded, but at the weekend Mr Hamilton said parts of its structure were still in place for a radically different purpose from the 1990s.
Mr Nesbitt said: “We must give consideration as to whether we need a new form of Independent Monitoring Commission that can take an independent look at the situation and give us confidence about what is going on out on the streets.”
Northern Ireland Secretary Theresa Villiers said the UUP took its own decisions.
She added: “The Government remains fully committed to the devolved political institutions and to the implementation of the Stormont House Agreement.”
That deal has been stalled by a political fallout between Sinn Fein and the DUP.
Ms Villiers said that she would be continuing discussions with parties about the impact of the murder of Mr McGuigan.