Relations between Stormont power-sharing partners the DUP and Sinn Fein have plummeted to a new low in the biggest crisis at the top of the devolved Government for years.
Sinn Fein has been left incensed by the shock withdrawal of backing for the Maze Peace and Conflict Resolution Centre, accusing First Minister and DUP leader Peter Robinson of caving in to hardline unionist opinion.
In a letter to party activists, the DUP leader said genuine steps towards a shared future would require a change of attitude by Sinn Fein "especially towards the innocent victims of IRA terrorism".
Sinn Fein sources said it was not informed privately about the DUP announcement ahead of Mr Robinson's letter being released to the media and has been left seething.
As Deputy First Minister Martin McGuinness returned to his desk at Stormont yesterday following a short holiday, it was made clear there was no direct contact between the two men at the head of Northern Ireland's partnership Government.
A senior Sinn Fein source said: "This is just typical of the DUP -- make an agreement, and then break it.
"Martin has no need to be contacting Peter, who is sunning himself in Florida. Martin can't even get him sometimes in Belfast.
"This is not our problem. The DUP did not even let us know about this in advance."
But it was also made clear the row does not raise a question mark over their joint trip to New York in September, which will go ahead as planned.
Mr McGuinness was making no comment yesterday, but Sinn Fein MLA Raymond McCartney, who was a former hunger striker in the Maze, said Mr Robinson's decision was "hysterical and cowardly".
"He pens a letter telling how he is standing up to the TUV and UUP, yet what he is actually doing is following the agenda they have set for him," he said. "It is further evidence of weak political leadership.
"He talks about building a consensus at the same time as he talks up a veto. It is a nonsensical position.
"Peter Robinson has not issued one word of condemnation about the violent attacks on the police in Belfast on Friday night. He has been silent on the attack on the Belfast Mayor," he said.
And he added: "It is up to the DUP to explain to people why, at a time of significant economic challenges, they are prepared to squander this opportunity for investment and job creation on the pretext that anti-peace unionism has mobilised against it."
But the DUP's Sammy Wilson, hit back: "There is absolutely no reason, except republican petulance, for the economic development of the Maze not to continue.
"The potential still exists for the 5,000 jobs which would make a huge impact on issues such as youth unemployment and the continuing battle to rebuild Northern Ireland's economy."
The former Finance Minister added: "Sinn Fein's response to the First Minister's letter continues to show just how out of touch they are with the feelings of anyone outside their republican clique."
In his letter, Mr Robinson concluded: "We have established a fundamental principle that the Maze site must be developed as shared space. If people will not share a street or road, it is self-evident that more work is needed to ensure equality in the way that the concept of shared space is taken forward."