Unionists have threatened to walk away from Northern Ireland's policing board if the British government allows ex-IRA prisoners to join new scrutinising bodies.
With Dublin and London desperate for Sinn Féin to endorse police arrangements and ease the deepening crisis in the peace process, critical legislation is set to be tabled within the next ten days.
Northern Ireland Secretary Mr Paul Murphy is considering lifting the block on jailed paramilitaries sitting on the District Policing Partnerships in a bid to win republican backing for the policing reforms.
Such a move could then pave the way for the IRA to meet British Prime Minister Mr Tony Blair's demand that it should disband.
But Mr David Trimble's Ulster Unionist Party and the Rev Ian Paisley's hardline Democratic Unionist Party tonight warned they will not tolerate any concessions.
Mr Jeffrey Donaldson, the UUP Lagan Valley MP, insisted his party was locked into a unanimous decision to withdraw from the board if more police reforms were introduced.
He said: "Convicted terrorists should not be allowed on to the DPP's.
"If the Government is determined to do this and think we will just roll over they are wrong."
PA