The Democratic Unionists have "done a U-turn" over sitting down with Sinn Fein in talks, Ulster Unionist leader David Trimble has said.
Mr Trimble said the DUP 'concealed the truth' from core supporters
Mr Trimble mocked DUP leader Ian Paisley's hints that he may now attend all the meetings of the forthcoming Good Friday Agreement review, even though it will feature round-table sessions with all the Assembly parties, including Sinn Fein.
He was addressing a meeting of Strangford unionists on Friday evening ahead of the review due to begin on 3 February, which will also involve the British and Irish Governments.
It is understood the DUP will defend its decision by arguing that the opening session of the talks will not be a negotiating forum, but merely an opportunity for each of the parties to state its opening position.
In a wide-ranging speech, Mr Trimble said the notion of the anti-Agreement DUP agreeing to sit at the same table as Sinn Fein would have seemed unbelievable during the election campaign.
He said the DUP would no doubt explain the move by insisting it was not actually negotiating with Sinn Fein but with the government.
"One cannot help but wonder if the DUP vote would have been so high if they had told the electorate that the U-turn on sitting down with Sinn Fein would begin almost immediately after the election," he said.
He added: "This is all a familiar part of the process whereby they conceal from their core support the truth about their actions."
Mr Trimble said he would be looking closely at any proposals the party put forward, but cast doubt on the DUP's ability to deliver any of its preferred models for devolution.
Secretary of State Paul Murphy and Irish Foreign Minister Brian Cowen met in Dublin on Thursday to discuss how to handle the forthcoming review of the Agreement.
Mr Murphy admitted it would be difficult to reach a resolution after the DUP and Sinn Fein emerged as the two largest parties in last November's Assembly elections, but insisted a breakthrough was possible during the review.
Mr Cowen said the review would focus on how the Agreement could best be fully implemented.
Both governments say they expect the review to last about three months, but no definite date for the end of the process has been specified.
The devolved administration at Stormont was suspended in October 2002 amid allegations of IRA intelligence-gathering in the Stormont government.