American firms have won 28% of Bechtel's £430m main infrastructure contract. Saudi Arabian firms have secured 18% and Iraqi companies just 16%. The remaining 20% of contracts have either not been awarded yet or have been distributed in small amounts.
Wilson revealed the figures in his capacity as Britain's special representative on trade opportunities to Iraq and Afghanistan.
In his first interview in the position, Wilson said there was progress being made in the rebuilding of Iraq but that the security threat should not be ignored.
He said he had been meeting British firms to help find out what their views were about working in the region.
Wilson added that he would be visiting Iraq in the near future, as soon as it safe to do so.
Wilson said that progress in rebuilding Iraq was linked to progress in making the country more secure.
He said: "Nobody would underestimate the safety issue, but it also emphasises why the reconstruction is so important. Rebuilding is needed so the region can move forward."
Wilson added that it was not his job to advise British firms on how to deal with the dangers of working in Iraq. He said there were security experts who could perform that role.
Wilson said he had been asked by prime minister Tony Blair to represent British interests because of his experience of international trade and the construction industry.
Wilson's comments came as Paul Bremer, the US administrator in Iraq, said it was "almost impossible to exaggerate" the country's economic needs.