The BBC's David Eades: "It is for the politicians to deliver a brighter future"

But it said it would only participate if former US senator George Mitchell can establish that republicans and loyalists are committed to exclusively peaceful means.

The Rev Ian Paisley's Democratic Unionist Party said on Friday that it would not take any formal part in the Mitchell review.

The BBC's Val Jones: "Both parties will consider their position"

But the party said it would accept an invitation to meet George Mitchell. The DUP, which opposes the Good Friday Agreement, also said it would closely monitor what happened in the review.

Ian Paisley said he hoped to meet Prime Minister Tony Blair during the first week of the review to discuss the peace process.

David Trimble: No question of terrorists in government

Ulster Unionist leader David Trimble said urgent action was needed to restore confidence in the peace process.

He said: There is no question of bringing terrorists into government and allowing them to keep on being involved in terrorism and then saying it is not as bad as it might be.

'Moral basis'

''That complete abandonment of any sort of moral basis and approach to things is what has caused considerable revulsion within the community and we must get back to basic principles.''

Mr Trimble's comments came as his party issued a statement outlining its terms for participating in the process.

Sinn Fein's Alex Maskey: David Trimble has responsiblity to form an executive with Sinn Fein

But Sinn Fein Assembly member Alex Maskey said the statement was another attempt to waste more time.

He said: ''David Trimble signed a pledge last July which committed him to building an executive and committed him to bringing his party because they have an electoral mandate on exactly the same terms as I have an electoral mandate.

''I have a responsibility to get my party in the executive and so does he. Let's get this smoke screen out of the way. Let's establish that we can get a proper review commencing on Monday.''

Sinn Fein's national executive is to meet on Saturday to decide if the party will participate in the review.

'Pre-requisite'

In their statement released on Monday morning the Ulster Unionist Assembly Party said dialogue could only be conducted with those who are genuinely committed to exclusively peaceful means.

Pressure on George Mitchell to assess "democrats and thugs"

The statement said: ''This is the essential pre-requisite for success and will determine our subsequent engagement in the review.

"Without establishment of a real commitment by all to exclusively peaceful means, ongoing participation in the Mitchell process would be without purpose."

The UUP Assembly Party intends to present a dossier to George Mitchell on breaches of the paramilitary ceasefires.

They said republicans had done anything but prove they were embracing a purely democratic policy in the past 15 months since the Good Friday Agreement was signed.

"Urgent action is required to restore confidence that the democrats, not the thugs and gangsters, will prevail in the establishment of the new institutions at Stormont," they said.

'Cancer at core of process'

Senior UUP Negotiator Sir Reg Empey said his party would ask Mr Mitchell to widen the review to establish whether the participants were committed to peaceful means because that doubt was a "cancer at the core of this process".

The BBC's Simon Jones: "Mixed measures for the future of the peace process"

He said: "If we can find tangible evidence that there is genuine commitment then that is the key to progress. It will avoid all the difficulties we are currently in.''

Seamus Mallon: Parties must stop playing games before review

Twelve senior UUP party officers including Mr Trimble, are due to meet on Friday and the party's ruling executive of around 100 members is to meet on Saturday to finalise policy regarding the review.

George Mitchell is due to start chairing the review on Monday. It follows the UUP's refusal to form a power-sharing executive at Stormont with Sinn Fein in July.