The decision came after a night of rioting throughout the province, which the Royal Ulster Constabulary described as "absolute madness". In Londonderry, where ferocious rioting led to one death, local police said it was as bad as anything they had seen in the whole 27 years of the Troubles.
Last night, the third night of rioting in Catholic areas, a republican mob attacked loyalist homes across the "peace line" in north Belfast with petrol bombs. Police said residents were fleeing their homes in Twaddell Avenue when, "as the situation became life-threatening", an RUC officer opened fire into the air to break up the mob.
Sporadic violence, petrol bombing of the police and car hijackings were continuing, but at a lower level than on previous nights.
From Dublin, however, the IRA appealed for calm while assuring nationalists it would not allow their areas to be "overrun".
The SDLP executive, meeting in Dungannon, concluded that following the events in Porta-down last week there was no longer any basis for the party's participation in the peace forum. The unionist parties will now be left virtually alone in a body designed to bring nationalist and loyalist views together.
SDLP leaders said they had reviewed the "grave" situation created by the Orange Order's defiance of the law and the Government's "capitulation" to threats of violence.
The party, led by John Hume, whose contacts with the Sinn Fein president Gerry Adams in 1993 began the present peace process, deplored the street violence. It called for restraint and for influential figures to prevent any further disorder, destruction, injury and loss of life.
Mr Hume last night asked for separate meetings with John Major, John Bruton, the Irish premier, and US Senator George Mitchell which would determine the SDLP's future attitude to multi-party talks.
The decision to quit the forum leaves open the possibility that the party could still take part in full talks, but it is unclear how sufficient confidence could be restored for them to take place.
Meanwhile, the London and Dublin governments continued their bitter exchanges yesterday. The Ulster Secretary, Sir Patrick Mayhew, launched a stinging attack on the Irish premier John Bruton, who had roundly criticised the British government on Friday night. He said that Mr Bruton had made an "offensive" outburst.
Dick Spring, the Irish Foreign Minister, replied that the Ulster nationalist community felt "abandoned and let down" by the British government. He called for an emergency meeting on Thursday of the Anglo-Irish Conference, a call backed by Labour's spokeswoman, Marjorie Mowlam.
Sources at the Northern Ireland Office, however, suggested that such a meeting was impractical.
Labour's bi-partisan support for the Government on Ulster seemed under considerable strain last night. Ms Mowlam, attending a Labour women's conference in Blackpool, said: "The Government's lack of political leadership and failure to take the initiative in the run-up to the parades this year created a situation last week where the RUC were left to make impossible operational decisions." There were also reports that she had pressed for an independent commission on provocative loyalist parades but that Sir Patrick Mayhew had bitterly resisted the idea.
However, Sir Patrick is considering the appointment of a senior judge to sit on a proposed advisory committee to consider march routes.
The rioting on Friday night led to inevitable fears of a full-scale return to IRA violence. There was widespread trouble in Catholic areas of Belfast and, in Strabane, police reported that rioters had tried to burn down the town centre.
Early yesterday, masked and armed IRA men appeared on the streets of Belfast and openly allowed themselves to be photographed.
In its Dublin statement, the IRA said that it "applauds the resilience and strength of nationalists in areas under virtual siege from the combined forces of this Orange statelet."Reuse content