A special Pentagon office created in the run-up to the Iraq war engaged in “inappropriate” activities by providing misleading intelligence to policymakers, according to the US Department of Defense.

The Pentagon inspector-general on Friday said the Office of Special Plans set up by Douglas Feith, then undersecretary of defence for policy, provided senior policymakers with “alternative intelligence assessments” on alleged links between al-Qaeda and Iraq that were “inconsistent with the consensus of the intelligence community”.