The prohibition, imposed after an unsuccessful personal intervention by Tony Blair, was the main development in a day of talks at Stormont which focused more on marching than on the key arms decommissioning issue.
This meant the talks edged ever closer to their Wednesday midnight deadline without particularly intense negotiations. One party leader emerged from the talks in mid-afternoon to say: "Nothing's happening in there yet. I'm going for a walk."
One view was that the talks would only come to life this afternoon, when an important report on decommissioning is due to be delivered. This is being drawn up by an international body on decommissioning, headed by the Canadian General John de Chastelain, who last week circulated all parties with a number of questions to be answered by noon today.
Parties were asked if any areas of implementation of the overall agreement would "demonstrably facilitate the decommissioning process", and whether they could help determine the willingness of paramilitaries to hand over weapons by May 2000.
Sinn Fein's response will be scrutinised for indications of whether and when the IRA might be expected to move on decommissioning. Pat Doherty, a senior Sinn Fein member, said intriguingly yesterday: "I think that could potentially start a process of us collectively coming to an agreement."
In the meantime, the security forces will proceed with carefully drawn up plans to seal off the countryside around Drumcree parish church to ensure that Sunday's march cannot reach the Catholic Garvaghy Road. More than a thousand troops have already been flown in from Britain.
Ominously, a loyalist bomb threat interrupted the news conference at which Alistair Graham, the Parades Commission chairman, was announcing the Drumcree ban. Portadown Orangemen later issued a statement expressing "bitter disappointment" over what they described as a failure by residents to respond to initiatives aimed at solving the dispute.
There is also much apprehension about Orange Order plans to have two large parades depart from their normal routes on 12 July to converge from on a Belfast flashpoint, the Catholic Lower Ormeau district. This would lead to thousands of Orangemen marching on a small and isolated nationalist ghetto.
The political talks appeared dependent on bringing maximum pressure to bear on both the Ulster Unionists and the republican movement to move towards a compromise. The US President, Bill Clinton, was again active yesterday, arguing that movement was necessary to keep the peace process alive.
The Ulster Unionist leader David Trimble said the proposed new coalition executive would be set up simultaneously with IRA decommissioning. He added: "We want a clear acceptance by the republican movement of its obligation to decommission. We are prepared to look at forms of sequencing but those sequences will involve actual decommissioning.
"What we want to hear first of all, clearly and unequivocally, no ifs no buts, is that republicans accept that they have an obligation to decommission and that they are going to do so within the timescale set out in the Agreement."
The Sinn Fein president, Gerry Adams, said: "We should not underestimate the seriousness of this last, critical stage of negotiations. Sinn Fein is here to do the business." He said a deal was possible if the Good Friday Agreement was implemented in full, but the Ulster Unionists' slogan "no guns, no government" was standing the peace accord on its head.Reuse content