Threats from Sinn Fein will stall negotiations on the devolution of justice powers, the DUP leader has warned..

This week Sinn Fein national chairman Declan Kearney stopped short of threatening the future of the Stormont administration but accused unionists and the government of playing fast and loose with the talks.

But Peter Robinson said republicans had become irrational about devolution of policing and justice.

"Sinn Fein needs to know that ushering little known placemen out to speak to the media and issue threats of Armageddon will only delay progress," he said.

"Any further threats will ensure negotiations are stalled. The DUP will not negotiate under threat.

"Sinn Fein should know what the consequences are as they tried this once before. It didn't work then and it will not work now."

In August 2008 Sinn Fein TD Caoimhghin O Caolain warned his party would collapse the Assembly unless there was progress on the devolution of policing and justice.

Mr Kearney said Prime Minister Gordon Brown and Secretary of State Shaun Woodward had failed to prevent Mr Robinson from creating obstacles to a deal.

Government has offered a package of nearly £1 billion to fund the transfer, but the DUP has said it will not move until community confidence in the Assembly taking-on such sensitive powers is secured.

But Mr Kearney warned: "The DUP's and British Government's short-term expediency has all the potential to push this impasse into complete free-fall - they still aren't learning the political lessons."

Mr Robinson said Sinn Fein had a tactic of arranging for one spokesman to publicly breath fire and damnation then sending out another to assure the public that it was not a threat.

"They know that what is left afterwards is the lingering odour of blackmail and they hope that others will fear the possibility that the dark decree may be the reality," he added.

"I will neither submit to blackmail nor negotiate in a climate of blackmail. The use of these tactics will bring negotiations to a halt."