The DUP has claimed the IRA has refused to seal permanently one of its arms dumps and avert a collapse of the Assembly.
The DUP justice spokesman, Mr Ian Paisley Jnr, said the British government had proposed the removal of two army watchtowers in exchange for a gesture on arms dumps. He claimed this had been rejected by the IRA.
Mr Paisley said the two watchtowers were in south Armagh but would not identify them more precisely for fear of divulging the identity of his military sources.
"According to my sources the IRA indicated that it wants movement on the watchtowers but rejected the request out of hand," he said.
"They said that under demilitarisation they should be closed anyway and not as part of some quid pro quo."
Mr Paisley claimed the new Ulster Unionist MP for South Antrim, Mr David Burnside, had misunderstood or misinterpreted information, possibly from similar military sources, that the IRA intended sealing a dump.
Mr Burnside, who said last week that such move would be insufficient, was not available for comment.
Mr Paisley said the IRA's alleged refusal indicated that despite the large anti-agreement vote at the Westminster and local elections, "the whole process remains a one-way conveyor belt process of concessions to republicans.
"Anybody who thinks the IRA is about to decommission is seriously, seriously wrong." Mr Paisley said comments by Mr Seamus Mallon and Mr David Trimble in London yesterday that the process was in crisis illustrated the need for new arrangements.
"It's the first time in a long time the First Minister and Deputy First Minister have been in agreement," he said. "We need something with durability. Mr Trimble's proposals are falling down around his ears."
Mr Paisley maintained the DUP, which is due to hold talks with Mr Blair on Thursday, had not been given the respect due to its new-found mandate. "The Secretary of State should be working with us to find a better way," he said.
Instead, the British were ignoring what the majority of unionists had voted for, "and the longer they do that the further this will go into crisis," Mr Paisley said.
Commenting last night, the Northern Ireland Secretary, Dr John Reid, said he hoped Mr Trimble would not feel that he had to step down.
Asked whether he expected Mr Trimble to quit, Dr Reid said: "That is a matter for David.
"I recognise, as many people do, the major contribution he has made to this process and would like to see circumstances where no one, David or anyone else, felt they had to resign . . . In order to get to that, we all have to face up to all of our responsibilities, every party and both governments," Dr Reid told Channel 4 News.
Earlier, with anti-agreement MP Mr Jeffrey Donaldson by his side, Mr Trimble said he had advised his UUP colleagues last year to back the Northern Ireland administration purely on the basis of republican promises that weapons would be put beyond use.
"That promise has not been kept and speaking personally, my patience is at an end on this issue. If we do not see the republican movement keeping their promise, I will vacate office in a fortnight's time."
Mr Trimble repeated his warning on leaving Downing Street. "I have made it absolutely clear that without this issue being resolved that will happen and I am doing it deliberately in order to bring the issue to a head because I am satisfied in view of the experience we have had, from the way in which Mr Adams and others have conducted (themselves), that given time he will waste it."
Mr Mallon emerged from the talks claiming the peace process was in "very big trouble and people should realise that".
He added: "Unless there is a very serious approach taken by the two governments with all of the parties then the institutions are in danger".