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The Butler report has criticised the informal style of Tony Blair's government as it took decisions in the run-up to war in Iraq.
None of Mr Blair's advisers was directly criticised
The report said the style of government "reduced the scope for informed collective judgement" and that cabinet ministers were not able to discuss issues properly as they were not given enough information.
Asked about the issue at the launch of the report, Lord Butler said there were many ways of conducting the machinery of government - and there was no suggestion Mr Blair's style was any less effective.
But the report concludes: "We are concerned that the informality and circumscribed character of the government's procedures which we saw in the context of policy-making towards Iraq risks reducing the scope for informed collective political judgement."
Lord Butler said the cabinet discussions - of which there were many before the decision to go to war in Iraq was announced - were based on information given in oral presentations.
The former Cabinet Secretary said there was no reason to assume the oral presentations were deficient but that they did not give ministers enough time or enough information.
The Butler report made no direct criticism of key figures within Tony Blair's inner circle, such as the chief of staff Jonathan Powell or former spokesman Alistair Campbell.
In March 2004, Cabinet Secretary Sir Andrew Turnbull dismissed claims that cabinet decision-making broke down in the run-up to the war in Iraq.
In evidence to the Commons public administration committee, he said there had been more discussion in Cabinet than there had been in the final years of Margaret Thatcher's government, but that more thought should be given to keeping records.