Junior Minister Jeffrey Donaldson said republicans stating their intention to topple the Stormont Executive if policing and justice powers are not quickly transferred from Whitehall would only harden unionist thinking.

"The Executive has not met for weeks now," he said – because Sinn Fein is blocking its business in the absence of devolution of the policing powers.

"That is undermining public confidence. They are damaging it and they are seriously damaging it," he said.

People need to see a "maturity" about the devolved administration, to know it can be trusted with something as crucial as policing and justice, and Sinn Fein was not displaying a political maturity.

He asked: "Do you think it builds confidence when people are threatening to pull the House down?"

Mr Donaldson said the DUP needed to know where the Sinn Fein leadership stands on the comments made by Irish TD Caoimhghin Ó Caolain and if they were representative of the party.

He added, however, "bearing in mind the statement went through their official press office, one is left with the impression it's a bit of kite-flying by Sinn Fein.

The Traditional Unionist Voice had a different take on the Sinn Fein threat, which leader Jim Allister said was just the latest round in the endless political games and concessions republicans have dealt in for two decades.

"It is time for the DUP to face reality. Belfast Agreement devolution has failed; mandatory coalition is unworkable," he said.

"The DUP has a clear choice – face reality and end the dysfunctional charade at Stormont or go on feeding the insatiable demands of IRA/Sinn Fein."

The MEP said what was clear from Sinn Fein's warnings was that it was not really interested in devolution, but what it could extract from the situation to further the cause of Irish unity.

"Recent events should demonstrate to even the slowest learner the utter folly of ever believing Sinn Fein had any interest in delivering good government to Northern Ireland, a state it does not believe in, nor can it bear to even speak its name. No self-respecting unionist should hang around this absurd system of government waiting to be blackmailed by political thugs in suits," said Mr Allister.

And he warned the DUP against any deal on policing, this autumn.

"No matter how it is dressed up", he said "conceding policing and justice now will be seen for what it is, abject surrender to the republican agenda for the sake of clinging to office."