Declan Kearney accused the DUP of making a serious political mistake
Sinn Fein has accused the DUP of a "train-wreck" strategy and having no intention of backing the transfer of justice powers to Stormont.
The comments came in a speech from Sinn Fein's national chairperson on the eve of talks on the devolution of justice between Gordon Brown and Brian Cowen.
Declan Kearney said the "evidence indicated" the DUP had no intention of backing the move.
He was speaking at an event in Dunloy commemorating two dead IRA men.
"Their continued intransigence is a serious political mistake," he said.
"It is a train-wreck political strategy and political consequences will be inevitable."
The DUP's Peter Weir said that his party would not be bullied by republican "sabre-rattling".
"As unionists we don't respond to threats - we'll be carrying on with the job of getting the conditions right for the devolution of policing and justice," he said.
Sinn Fein expressed frustration at the government and the DUP
"We're not going to be looking at the time-frame, we're looking at the conditions."
Earlier, Deputy First Minister Martin McGuinness said a date for the transfer of policing and justice powers to Northern Ireland must be set before Christmas.
The DUP and Sinn Fein have been arguing for months over the issue, often referred to as the "last piece of the devolution jigsaw".
Mr Brown, the UK's prime minister, is to discuss the issue with Taoiseach Cowen on Monday.
"What is required is a date to be agreed prior to Christmas for the transfer to take place and to take effect early in the New Year," Mr McGuinness said.
He said that "ongoing attacks" by First Minister Peter Robinson, who leads the Democratic Unionist Party, on the decision-making processes were of concern.
"I see these attacks as a very clear example of the failure on the part of the DUP to embrace the equality, partnership and power-sharing arrangements which lie at the heart of these agreements ," he said.
Mr Robinson has said that he wants community designation replaced by a 65% weighted majority system to "ensure widespread support" but which would stop any single party having "a veto on progress".
"It would encourage co-operation and compromise and end the potential of blackmail by stalemate," he told a DUP meeting in Foyle last week.
The DUP leader has said policing devolution will only take place when there is sufficient community confidence.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.