A BBC investigation estimates around US$23bn may have been lost, stolen or just not properly accounted for in Iraq.
The BBC's Panorama programme has used US and Iraqi government sources to research how much some private contractors have profited from the conflict and rebuilding.
A US gagging order applying to 70 court cases against some of the top US companies, prevents any discussion of the allegations.
Henry Waxman, who chairs the House committee on oversight and government reform, said: "The money that's gone into waste, fraud and abuse under these contracts is just so outrageous, it's egregious. "It may well turn out to be the largest war profiteering in history."
As an example, in the run-up to the invasion, one of the most senior officials in charge of procurement in the Pentagon objected to a contract potentially worth $7bn that was given to Halliburton, a Texan company which used to be run by Dick Cheney before he became vice-president. Unusually only Halliburton got to bid - and won.
The BBC aired the programme on Panorama. The video was posted on Google Video, but later removed. (Full)
More articles on the Road about Iraq.
Cartoon courtesy People's Geography