The IRA may have offered to decommission weapons in tandem with a withdrawal of British military bases from sensitive republican areas, the implementation of the Patten report on the RUC and the reform of the North's criminal justice system, according to informed sources.
The IRA offer, which caused Gen. de Chastelain to issue his positive appraisal of the prospects for decommissioning last Friday, was off the table last night, however.
In its statement confirming it had withdrawn its interlocutors with the Independent International Commission on Decommissioning (IIDC), the IRA said it was also withdrawing "the propositions put to the IIDC by our representatives".
This was described as a considerable setback by sources close to the negotiations last night.
However, there was no immediate concern that the IRA was considering returning to a military campaign, the sources said.
It was expected last night that Gen. de Chastelain would explain the reasoning behind last Friday's positive report to the Ulster Unionist leader, Mr David Trimble, during their meeting last night. The meeting had been encouraged by Irish negotiators in the hope that the general could convince the unionists of the IRA's "positive" intentions.
Sources close to the negotiations said the IRA is understood to have stated that decommissioning could take place so long as the terms of the agreement concerning the de-escalation of the British military presence in the North, the reform of the RUC and the criminal justice system were implemented. Any IRA decommissioning is unlikely so long as the British army maintains its high-profile presence in areas such as south Armagh and east Tyrone.
Republicans are also eager to see the implementation of the Patten recommendations which were substantially accepted by the British government.
They also wish to see the reform of the North's extensive "emergency" or "anti-terrorist" legislation, which allows seven-day detention for questioning.
The removal of the Diplock jury-less court system is another issue for the IRA.
Meanwhile in Washington, the White House vowed to keep on trying to mediate in the Northern Ireland peace process but acknowledged that the IRA's statement of its withdrawal was a setback.
"Obviously, we regret any indication of backtracking on the recent progress that was made in establishing clarity on decommissioning," White House spokesman Joe Lockhart told reporters.
"We're going to continue to work this from all sides," he said. "And you know, obviously this is not a positive development, but it's not a reason to give up on the process."