The Democratic chairman of the US Senate Armed Services Committee has suggested intelligence was twisted in the run-up to the war in Iraq.
Mr Feith left the Pentagon in 2005, admitting doubts about Iraq
Carl Levin was reacting to a report by the defence department's top watchdog, Inspector General Thomas Gimble.
The report accuses a former top Pentagon official of running an alternative intelligence operation.
Mr Gimble said Douglas Feith's office had not acted illegally but some of its activities had been "inappropriate".
Sen Levin suggested Mr Feith's office had reached sought to establish a link between Saddam Hussein's regime and al-Qaeda - although the official intelligence community was more cautious - in order to bolster the administration's case for war.
Under repeated questioning by Sen Levin, Mr Gimble said the conclusions reached in reports by Mr Feith were not fully supported by the available intelligence.
In particular, his conclusion there was a "mature and symbiotic relationship" between Iraq and al-Qaeda could not be justified on the basis of the available intelligence.
And an alleged meeting between an Iraqi intelligence officer and a leader of the 9/11 attacks, Mohamed Atta, never took place.
Sen Levin suggested this proved intelligence had been twisted before going to war.
Ike Skelton, Sen Levin's counterpart in the House of Representatives, blasted Mr Feith after the inspector general issued his report.
"Doug Feith and others in that office exercised extremely poor judgement for which our nation, and our service members in particular, are paying a terrible price," he said in a statement.
Mr Feith told the inspector general his reports never pretended to be intelligence assessments, the report's executive summary says.
He added that even if they had been, they would have been appropriate because they were authorised by his superior at the Pentagon.
Mr Feith's supporters stress that the inspector general found no evidence of illegal or unauthorised activity.
The inspector general's report does not recommend that any action be taken, given that the US has reorganised its intelligence services since 2002.
The full report is classified. Sen Levin is urging that it be made available to the public.