The Ulster Unionist leader, Mr David Trimble, has said his party will not be treating Sinn Fein as a normal political party during Mr George Mitchell's review of the implementation of the Belfast Agreement which begins at Stormont today.
The UUP decided to take part in the review after a meeting of its 100-member executive on Saturday. Mr Trimble was in favour of participation. However, it is understood there was only broad and not unanimous support for this position at the meeting.
The UUP Assembly party was also in favour of participation, although the majority of UUP Westminster MPs were either against it or had serious doubts.
Speaking after the meeting, Mr Trimble said there was "deep scepticism" in the UUP about the commitment of republicans and loyalists to exclusively peaceful and democratic politics. "The approach by the [Ulster Unionist] Assembly party was broadly supported. At the same time, we are making it clear that as far as Sinn Fein is concerned, it will not be business as usual," he said.
He stressed that the UUP's participation would be kept under constant review. It is understood that the party's deputy leader, Mr John Taylor, indicated at the meeting that he would not be joining his colleagues in the review because of recent Provisional IRA violence.
The anti-agreement MP, Mr Jeffrey Donaldson, said the UUP would be insisting that all parties which participated in Senator Mitchell's review were committed to "exclusively peaceful means".
"There is no basis for moving forward to enter into government with Sinn Fein/IRA as long as it is engaged in violence," he said. "There must be an end to murders, bombings, shootings, gunrunning, racketeering and intimid at ion, an end to expulsion orders and the progressive dismantling of paramilitary organisations.
"These were the words of the Prime Minister, Tony Blair. That's what I want to see and without them, the commitment is not there."
Mr Donaldson said it would not be sufficient for other participants in the process to take Sinn Fein and the fringe loyalist parties at their word. "Words are not enough," he said.
There needed to be "tangible evidence" in the form of decommissioning and a total end to paramilitary violence for the peace process to work.
Meanwhile, Mr Trimble also said his party's executive would meet following the publication on Thursday of the report by the Independent Commission on Policing which is chaired by the former Hong Kong governor, Mr Chris Patten.
"It is perfectly obvious that if Patten gets it seriously wrong that will have serious implications for the whole process."
