The DUP was last night under mounting pressure to clarify exactly what it will take for them to agree to devolving policing powers to Stormont.

The demand from Sinn Fein came after Jeffrey Donaldson said a decision to axe a police reserve unit could potentially scupper negotiations to transfer law and order responsibilities from Westminster.

The Lagan Valley MP's remarks followed comments by First Minister Peter Robinson two weeks ago that changes had to be made to how contentious Orange parades were managed before his party signed up.

Republicans claim both issues are preconditions the DUP have thrown into the mix at the last minute in a bid to delay devolution in the face of opposition both inside and outside the party.

Sinn Fein Junior Minister Gerry Kelly said neither matter had been identified as a make or break issue by the DUP until after the outstanding financial problems were resolved when Prime Minister Gordon Brown last month offered £1bn to support the new justice ministry.

“If you look back at Arlene Foster (DUP Economy Minister) a few weeks ago she said none of these things were preconditions,” he said.

“Then a couple of weeks ago we get the parades as a precondition, then we get Jeffrey Donaldson today saying the retention of the full-time reserve is a precondition.

“Depending on which one of the DUP is speaking they are saying something different.”

While Mr Kelly said the DUP's stance had created “very difficult circumstances” within the Executive, he rejected as “foolish” speculation that republicans would walk away from the power-sharing institutions if progress was not made.

The latest stumbling block emerged after PSNI Chief Constable Matt Baggott confirmed last week that the 380-strong full-time reserve force would be phased out by March 2011.

The DUP and other unionists have criticised the timing of the move given the increased threat from dissident republicans. Mr Donaldson said there had to be confidence within the unionist community before devolution could happen — and that axing the reserve was one of a number of issues that was undermining that confidence.

“We believe that in the absence of resolving this matter (the reserve) and some other issues like parades and PPWs (personal protection weapons) and so on, that the public confidence simply isn't there to allow devolution to proceed,” he said.

“The precondition is building public confidence, and these are the issues that help to build public confidence.

“So, the whole package is a precondition because building public confidence is a precondition,” he added.