As lord chancellor, Lord Irvine can and does sit to hear criminal and civil appeals from lower-ranking judges.

When he chooses, he also presides over the law lords - senior judges who also take part in parliamentary business.

There are calls for judges to be removed from the Lords

Last month the respected lawyers' reform group Justice said the lord chancellor should no longer sit as a judge - and judges should no longer sit in Parliament.

But in a speech to some 40 judges at the Worldwide Conference of Common Law Judges in Edinburgh, Lord Irvine said he saw no reason why he should not sit as a judge.

It was also important that the lord chancellor should sit as head of the judiciary, he said.

Independent judges

He said: "Provided that the lord chancellor has abstained from expressing any concluded views on an issue coming before him judicially and does not sit in any case where the interests of the executive are directly engaged, there is no reason at all why he should not sit and preside judicially."

He emphasised the independence of UK judges who were appointed on merit and did not depend on the government of the day for goodwill or for job security.

Lord Irvine praised the law lords' contribution to House of Lords debates on the administration of justice and their contributions to select committees.

Lord Irvine: Defends judges sitting in the Lords

He said that their judicial impartiality was preserved because, by convention, the law lords avoided making any comment in Parliament on issues likely to come before them judicially.

Lord Irvine said that the government would listen carefully to views expressed by the Royal Commission on the Reform of the House of Lords which is considering the long-term future of the upper chamber.

But at present it was not persuaded that a supreme court should replace the law lords as the highest appeal court, he continued.

Lord Irvine: " I am a constitutional reformer"

Earlier, Lord Irvine told the BBC most judges supported the office of lord chancellor.

He said: "They recognise the executive is very powerful, the government is very powerful in Parliament, but the judicial arm is correspondingly weak.

"Their duty is to ensure that the executive, the government of the day, is kept subject to the law.