Lord Chief Justice Sir Brian Kerr was expected to emphasise the independence of the judiciary as he gave evidence to the special committee examining the transfer of policing and justice powers to Stormont.

The top judge was making a rare public appearance outside the courtroom after being asked to give evidence to a Stormont committee.

But it was anticipated Sir Brian would refuse to comment on the timing for powers to be devolved, as the long-running row between the DUP and Sinn Fein over the issue continued.

A written submission to the committee, released before today's hearing in the Senate chamber, said: "The Lord Chief Justice wants to emphasise the importance of judicial independence as a constitutional principle and the need for judges to be outside political influence."

Written by Sir Brian's personal secretary, it also stressed a new Department of Justice should consult the judiciary on any proposals which would impact on it.

There should further be a protocol with First and Deputy First Ministers Ian Paisley and Martin McGuinness on any judicial appointments, it said.

The committee, chaired by the DUP's Jeffrey Donaldson, has until February to table a report on the necessary preparations to facilitate a smooth switch of justice and policing responsibilities.

Sinn Fein insists the Government's target of next May, which arose from the St Andrews negotiations almost a year ago, can still be met. But the DUP argues that is unlikely because there will not be sufficient public confidence by that time.

The committee's deputy chairman, Sinn Fein's Raymond McCartney, said the transfer was a "natural progression" following the restoration of devolution last May.

"None of the criminal justice agencies see any reason why it shouldn't be as soon as possible," he said.

But Mr Donaldson insisted his party will use its veto if necessary. Quoting the recent Belfast Telegraph opinion poll, which showed only 14% of the public supporting the May date, he said: "As things stand at the moment (it will not happen).

"(The DUP) has secured a triple lock. The First Minister has to approve the devolution; then it has to get approved by the Assembly on a cross-community vote; and then by Parliament."