Ulster Unionist Party MP Mr David Burnside has claimed people should brace themselves for another "con job" from Sinn Féin.
The South Antrim MP said: "Whilst the two unionist parties quite rightly are positioning themselves not to be in the losing end of the blame game following Leeds Castle, both the DUP and my party should realise that the governments are continuing in their appeasement of republicanism."
"Demands on on-the-runs, the Finucane inquiry, demilitarisation including the end of helicopter surveillance and intelligence-gathering are what is going to happen. "Also we must be alert to more appeasement on policing," he said.
"Unionists should not be fooled by republicans whose word is not to be trusted. P O'Neill can say what he wants. Why should he be believed?"
His comments came as the UUP prepared to produce a paper on the way ahead in Northern Ireland's deadlocked political process.
British and Irish Government officials are considering proposals that they hope will break the deadlock between the parties over future models for power-sharing, which has stalled an overall peace process deal.
At the end of last week's Leeds Castle talks in Kent, the British Prime Minister Tony Blair and Taoiseach Bertie Ahern believed a resolution had been achieved on the issues of IRA disarmament and paramilitary activity - which have frustrated a return to devolution for the past two years.
Republicans have insisted armed groups will disappear if politics in Northern Ireland is allowed to function properly and delivers equality.
PA