The Ulster Unionist leader, Mr David Trimble, walked out of the political talks at Stormont yesterday, citing a Government document which stated that the Provisional IRA was still acquiring weapons, targeting and recruiting.
"The people of Northern Ireland would not understand if we sat around that table talking as if nothing had happened in a situation where it has been clearly shown that republicans have been in breach of their ceasefire and breach of the agreement. As a result, we withdrew," he said.
The Progressive Unionist Party, the UVF's political wing, and Mr Bob McCartney's UK Unionists also left the talks at Parliament Buildings.
Mr Trimble said there were now clear grounds for the exclusion of republicans. The onus was on the British government to take action. He wanted to hear what Mr Blair had to say but, more importantly, to see what he would do.
Mr Trimble said he wasn't "looking for an instant reply or a bit of Band-Aid to cover-up the problem".
"We will await a formal government response and then consider what we do in January," he added. He said that since the document about continuing Provisional IRA activity was an Irish Government paper which quoted the British government, it was obviously "the view of both governments".
The British government had last year said that the gathering of intelligence and acquiring of weapons would be considered breaches of the ceasefire, leading to exclusion, Mr Trimble stated.
"Rather than chit-chattering as if nothing had happened, it was more appropriate to call a halt to our participation in \ discussions and call upon the governments to explain themselves," he added.
Sinn Féin president, Mr Gerry Adams, expressed disappointment at the unionist walk-out. He said some people would be outraged at what had happened.
He refused to be drawn on the Government document or whether the Provisional IRA was still targeting and recruiting. He said he had read the allegations in the newspapers. It was "as clear as the noses on our faces" that the IRA represented no threat to the peace process. The only threat came from "unionist paramilitaries".
He pointed to the ongoing sectarian violence against nationalists in flashpoint areas and to the internal UDA feud. Mr Adams described the unionist walk-out as "theatrical".
The talks were part of a process of change and there were certain matters which needed the involvement of unionism, he added. However, Sinn Féin had a mandate, and it was a question of "rights and entitlements" for the party and its voters, not concessions.
He expressed concern that the British government had admitted that parts of the Belfast Agreement still had not been implemented.
SDLP leader, Mr Mark Durkan, said the unionist walk-out had not been helpful. It would not have a positive effect on confidence and it did not alter the political agenda one iota. "You deal with serious issues by sitting around the table and confronting them. You do not walk out," he said.
In a reference to the departure from the talks yesterday of the leaders of the UUP, the PUP and the UK Unionists, he said: "Maybe after Christmas we will see the return of three wiser men." Mr Durkan said he hoped the talks would resume in the New Year and that serious issues could be addressed. Ms Monica McWilliams of the Women's Coalition expressed disappointment at the unionist walk-out. "This is not the message we wanted to send out in the last round table meeting of the talks before Christmas," she said.
"There is a huge frustration on our part that people continue to behave like this by walking out of rooms where serious problems must be dealt with.
"We wanted those people to stay. The more serious the issues, the greater the onus should be on them to stay."