The Government will come under pressure to end the deadlock over the devolution of policing and justice powers to the Northern Ireland Assembly.

Sinn Fein said Deputy First Minister Martin McGuinness are to use a Downing Street meeting with the Gordon Brown to warn that it was "unacceptable" that the Democratic Unionist Party (DUP) had failed to agree a date for the move.

After Mr Brown's recent offer of a £1 billion package to fund the transfer of the powers, Mr McGuinness warned that failure to agree a deal before Christmas risked "deep trouble" for the political process.

Conor Murphy, a Sinn Fein minister in the Stormont power-sharing government, said: "The negotiations on the financial package for transferring policing and justice powers concluded some weeks ago. People rightly expected there to have been further movement before now.

"To date the DUP despite signing on for transfer at St Andrews, agreeing to a process to see it happen last year and finalising the financial package have yet to make the decisive step and agree a date for transfer.

"This is unacceptable. Agreements reached in political negotiations need to be honoured."

The transfer of the powers would establish a new Justice Ministry at Stormont in an administration led by the DUP and Sinn Fein, which share the top political post of the joint Office of First Minister and Deputy First Minister (OFMDFM).

But DUP leader and First Minister Peter Robinson has said he will only agree to a deal when his party is ready.

He has sought concessions on the future stewardship of Orange Order parades in Northern Ireland, plus the future of the police reserve and access to personal protection weapons for former security force members.

Sinn Fein has accused the DUP leader of stalling on a deal and of failing to face-down hardliners inside his party, plus political rivals in the hardline Traditional Unionist Voice (TUV) party, who oppose any compromise with republicans on the issue of devolving law and order powers to the power-sharing administration.