The investigation into a possible NIO cover up is not a fully fledged legal inquiry, the Attorney General's office has confirmed.

Peter Scott QC was appointed last week to review whether the NIO attempted to pervert the course of justice in a High Court case about the Victims' Commissioner appointment.

But the barrister has not been given powers to compel witnesses or summon documents - and it remains unclear if he will interview Secretary of State Peter Hain and the senior civil servants at the centre of the affair.

A spokesman for Attorney General Lord Goldsmith said an advantage in Mr Scott conducting a review, rather than a full formal inquiry, is the " relative speed" in producing a report.

Mr Scott, who shared chambers with Lord Goldsmith when he was a practising barrister, was asked to review the case after Mr Justice Girvan said there was evidence the NIO deliberately misled the court.

After ruling last month that the appointment of Bertha McDougall was an illegal concession to the DUP, the judge suggested there had been attempt to cover up the DUP's role.

He criticised the NIO's two most senior civil servants and referred the matter to the Attorney General, noting that a deliberate attempt to mislead the court would be a crime.

In making his referral, Mr Justice Girvan posed 67 questions about the handling of the case - some of them asking what Mr Hain knew about the affair.

The Secretary of State read and approved the statements that the judge described as misleading.

Lord Goldsmith indicated to the House of Lords that he does not believe full powers were necessary because the NIO had agreed to co-operate completely with Mr Scott's review.

But he said he will "reconsider the situation" if Mr Scott expresses any concern.

Mr Hain says the department will co-operate fully, adding that "there is absolutely no question of any deliberate attempt to mislead the court or anyone else".

Mr Scott has declined to comment on the way he will conduct the review, and the Attorney General's office said it could not specify whether or not he will interview Mr Hain and the civil servants involved in the matter.

Legal experts say there may be complications in any interview, because the people involved could demand legal representation.

However, that does not rule out further action if Mr Scott recommends it in his report.

Lord Goldsmith said he intends to publish the report, which is not expected until the New Year.

But the Attorney General said some "issues may arise that might limit or delay" publication, such as "if for any reason it were to lead to disciplinary or other proceedings following from it."