Foreign Secretary David Miliband has conceded that the Iraq war inquiry would be able to apportion blame for what happened when it draws up its final report.

In what was seen as a further concession in the face of widespread criticism of the way the inquiry was set up, Mr Miliband said it would be able to “praise or blame whoever it likes”.

In his initial statement announcing the inquiry last week, Prime Minister Gordon Brown told MPs that its role would be to establish what lessons could be learned from the conflict and not to apportion blame.

Mr Brown has already been forced to give ground and accept that evidence sessions will be held in public, having originally announced that they would be conducted behind closed doors.

Opening an opposition day debate on the inquiry for the Government, Mr Miliband told the Commons it was still the Government's intention that it would not be a full judicial inquiry and would not be able to establish criminal or civil liability.

But, pressed by Conservative former foreign secretary Sir Malcolm Rifkind on the question of apportioning blame, he said: “It can praise or blame whoever it likes.”

Mr Miliband also denied that the Government originally opted for closed hearings because of Tony Blair's unwillingness to give evidence in public.

He said the former prime minister told a question and answer session on Tuesday night: “There is no problem for me answering questions in public.”

Earlier, Downing Street said Mr Brown would have “no difficulty” in giving evidence about his involvement, providing that national security considerations could be met.

Mr Miliband sought to reassure MPs that the inquiry chairman, Sir John Chilcot, had agreed that “as much of possible” of the inquiry would be held in public.

“‘As much as possible' means that as much as possible will be in public,” he said.

However, he faced repeated interventions, including from Labour MPs.

Backbencher Gordon Prentice said a briefing note circulated to Labour MPs by Mr Miliband's office had stated that the inquiry would “sit in private with scope for public events.”