BBC News' Denis Murray: George Mitchell's task looks more difficult than ever

The party has also delayed a decision on whether to seek a judicial review of the UK Government's verdict that the IRA ceasefire is still intact.

After meeting with the Ulster Unionist Assembly group in Belfast on Tuesday, UUP leader David Trimble said the key question was not what his party would do next, but what the paramilitaries would do.

He said: "We will not have a real peace unless the paramilitaries, all of them, are prepared to change.

"And now in view of what has happened over the summer there are very serious questions in relation to this and nobody is going to agree to live inside a Mafia state.''

Party leader David Trimble: "Our view is that the government made a mistake"

Mr Trimble added that both loyalist and republican ceasefires had been broken, but he said the difference was that while both sides had carried out attacks, the IRA had allegedly been involved in importing more weapons into Northern Ireland.

UK Prime Minster Tony Blair has said he supports Northern Ireland Secretary Mo Mowlam's position on the IRA ceasefire.

Mr Blair is seeking assurances from the parties that they are committed to the review, due to begin on Monday under the chairmanship of former US Senator George Mitchell.

But the leader of the anti-Agreement Democratic Unionist Party has called on the Ulster Unionists to face up to the IRA and break off all contacts with Sinn Fein.

Ian Paisley also said Dr Mowlam's days as secretary of state were numbered.

He said: "The secretary of state has surrendered to the violent elements. And that being so she has no future in any so-called peace initiative in Northern Ireland.''

Deputy UUP leader John Taylor and East Londonderry MP William Ross have also suggested that the Ulster Unionist break contact with Sinn Fein.

Sinn Fein's Alex Maskey: Valuable time has been lost

Sinn Fein's Alex Maskey said he hoped their discussions with the UUP would continue.

He said they should not be seeking any further excuses, as there were outstanding issues to sort out.

He said: ''The main concern that people have had in the last 16-17 months is that we are continuing to lose very valuable time.

''The momentum has gone completely out of the Good Friday Agreement and indeed now many people would now even question its entire credibility, so the notion of a deferring the review would be a serious matter.''

Sinn Fein has not yet said whether it will attend the review.

'Last chance'

But David Ervine, of the Progressive Unionist Party, which has links with loyalist paramilitaries the UVF, said both Sinn Fein and the Ulster Unionists must be there.

He said: ''Shame on anyone who isn't because for our generation this is the last chance.

''You won't get a chance to re-review this review. George Mitchell is standing behind the bar in the Last Chance Saloon.''

The SDLP's Mark Durkan: We must make the Agreement work

The SDLP's Mark Durkan has also called on the parties to end the guessing game.

He said: "If we are going to make the Agreement work we need to get our act together. We won't get our act together if we are seen to be running away from talks or trying to avoid each other."

Concern about the review of the failure to set up a devolved Northern Ireland government in July has been heightened by what Ulster Unionists have called a "crisis" in the peace process and security situation.

The UUP has discussed breaking contact with Sinn Fein following allegations that the IRA has expelled youths from the province with death threats, murdered a north Belfast man and been involved in an attempt to smuggle arms to Ireland from Florida.