Iraq hearings may be held in public

The Prime Minister's spokesman said that it had never been "an issue of theology" for the Government whether hearings were held in the open or behind closed doors.

He said that it would be up to the inquiry chairman Sir John Chilcot to decide how it should be structured in order to achieve its objective of establishing the truth of what happened.

He stressed however that the Government did not want to see a lengthy public inquiry like the Saville Inquiry into the Bloody Sunday killings which went on for years involving "countless lawyers".

In a letter to Sir John, Gordon Brown said it was essential witnesses to the inquiry were able to give evidence with "the greatest possible candour and openness" while maintaining "full public confidence in the integrity of the process" and not damaging national security.

"Once you have met, as I have suggested, the leaders of the other political parties and the chairs of the relevant parliamentary select committees it would be helpful if you could set out how you and your colleagues think these objectives can best be met in the way that the inquiry is conducted," he said.

Mr Brown said he hoped Sir John would consider whether it was possible for witnesses to give evidence on oath.

He suggested Sir John and his inquiry team should meet the relatives of the service men and women who had died in Iraq - either in public or in private - to explain how the inquiry would operate.

He also urged Sir John to hold an open session to "explain in greater depth the significant scope and breadth of the inquiry".

Mr Brown disclosed he had written to all relevant current and former ministers to "underline the importance of their full cooperation". Meanwhile, Cabinet Secretary Sir Gus O'Donnell was writing to Government departments informing them of the need for "full transparency".