Northern Ireland's First and Deputy First Ministers Peter Robinson and Martin McGuinness appeared to clash in public today for the first time over the devolution of policing and justice powers.
As the pair appeared before the cameras at a press conference their private disagreement over the devolution of policing and justice powers to the Stormont Assembly deepened when Mr McGuinness accused his counterpart of raising roadblocks to a deal.
As the men stood side-by-side in front of the media, a visibly angry Mr Robinson effectively reprimanded his opposite number accusing him of bringing private details into the public domain.
The temperature rose as Mr McGuinness continually shook his head in disagreement as Mr Robinson spoke.
The Sinn Fein leader hit out at Democratic Unionist Party (DUP) calls for a scrapping of the Parades Commission, which rules on Orange Order parades, and said it could not be a pre-condition to a deal on the transfer of policing and justice powers.
Mr McGuinness: "I move forward against the backdrop of the agreements that I made with Peter Robinson 13 months ago where we agreed an over-30 step approach to the transfer of powers on policing and justice.
"I have to say at no stage in that process was the issue of issues being used as pre-conditions for the transfer of power for policing and justice mentioned."
In a reference to a DUP letter to the Prime Minister demanding 'confidence building' measures for unionists before a deal, Mr McGuinness added: "At no stage were people contemplating sending, on solo runs, letters to Prime Ministers which effectively I had not seen, was not made aware of and was completely surprised by."
Mr Robinson hit back by claiming republicans had already backed reform of parades, but had now opted to delay the measures as a tactic.
The First Minister, who glanced at his adviser and became visibly angry as Mr McGuinness spoke, added: "I regret the tone of the latter remarks.
"I don't think that it is helpful for us to be going into the finer details of these matters, but nobody is in any doubt that the issue of parades was moving forward and was held back."
The exchanges were seen as a public demonstration of the two leaders' long-running private dispute.
Mr McGuinness is already on record as having said that he has not been able to build an adequate relationship with Mr Robinson, despite having enjoyed a good working relationship with his predecessor as DUP leader, Ian Paisley.
The clash came as Irish premier Brian Cowen lead a team of his government's ministers in a session of cross-border talks with members of the Northern Ireland administration.
The 'North-South Ministerial Council', first formed under the Good Friday peace agreement of 1998 is marking its tenth anniversary, but proceedings today were overshadowed by fears for the future of the Stormont Assembly.
Today's meeting in Limavady, Co Londonderry, brought together ministers drawn from both jurisdictions in Ireland who announced progress on a series of cross-border projects.
The Irish government delegation led by the Taoiseach Mr Cowen included seven other ministers: Tanaiste Mary Coughlan, Finance Minister Brian Lenihan, Foreign Affairs Minister Micheal Martin, Education Minister Batt O'Keeffe, Agriculture Minister Brendan Smith, Minister for Community, Rural and Gaeltacht Affairs, Eamon O Cuiv and Transport Minister Noel Dempsey.
The delegation led by the First and deputy First Minister included the DUP's Junior Minister Robin Newton.
The remainder of the Northern Ireland delegation was made up of Mr McGuinness, and his party colleagues Junior Minister Gerry Kelly, Regional Development Minister Conor Murphy, Education Minister Caitriona Ruane, plus the SDLP's Social Development Minister Margaret Ritchie.