Sinn Fein's meeting with British Prime Minister Tony Blair was cancelled today due to adverse weather conditions in London.
A party spokesman said it was hoped the meeting at Downing Street would now take place tomorrow at 3.30pm.
The decision means that a meeting which Sinn Fein leader Gerry Adams hoped to hold with Ulster Unionist leader David Trimble tomorrow will now most likely be held at the beginning of next week, the spokesman added.
The delay will not be welcomed in the North where there are fears Downing Street's attention will soon switch away from the North as war in Iraq looms.
The meeting with the delegation led by party president Mr Gerry Adams was due ot take place against the backdrop of the withdrawal of the Progressive Unionist Party from the talks process.
Party leader Mr David Ervine, whose party has links to the Ulster Volunteer Force and Red Hand Commandos, said his colleagues could not be expected to "rubber-stamp" a deal they had no sight of during negotiations.
"It is clear there are things going on in the undergrowth - both political and paramilitary," the East Belfast MLA said.
"Unless we have a clear understanding, a clear sight of what those are it would be foolish for the PUP to take its place in the upcoming talks and be used simply for a pat on the head and to rubber-stamp something we have not been party to.
"We are not prepared to play that game."
Mr Blair's meeting with Sinn Féin was part of a series of discussions this week with Northern Ireland political leaders.
He is due to meet Mr Mark Durkan, leader of the SDLP, in London tomorrow.
Although Whitehall sources insist the Prime Minister is fully engaged with efforts to revive the Assembly and power-sharing executive, it is believed in Belfast that the possibility of a war with Iraq gives Northern Ireland's politicians little time to cut a deal.
Ulster Unionist leader Mr David Trimble, who met the Prime Minister yesterday, has demanded an end to all paramilitary activity by loyalists and the IRA.
"We need to see republicans completing what they should have done in May 2000," the Upper Bann MP said.
"That means they must decommission visibly and transparently and agree to wind up their paramilitary organisations."
However as Sinn Féin prepared for its meeting in Downing Street today, party chairman Mr Mitchel McLaughlin urged unionists to work with them in creating the conditions for the removal of the gun from politics in Northern Ireland.
PA