They donated more to Bush's 2000 election campaign than they gave any other politician in the past 12 years, reveals the new study released on Thursday.
Researchers at the Washington-based watchdog group the Centre for Public Integrity said US contractors with multibillion-dollar contracts to rebuild the war-torn countries also enjoyed influential military and political connections.
The report did not accuse the firms or US agencies of corruption.
Bush was on the fundraising trail
again, on Thursday
It detailed more than 500,000 dollars in donations to Bush's 2000 campaign coffer from 70-plus US firms and individual contractors now active in Iraq and Afghanistan.
The same donors have garnered up to eight billion dollars in reconstruction business, the report said.
Many deals were not put out to tender as contract-issuing agencies - chiefly, the Pentagon, State Department and US Agency for International Development - said needs were too urgent to allow for time-consuming competitive bids, the report said.
"Nearly every one of the 10 largest contracts awarded for Iraq and Afghanistan went to companies employing former high-ranking government officials or individuals with close ties to those agencies or Congress"
Centre for Public Integrity report
State Department spokesman Richard Boucher said the agency had yet to review the report in detail but rejected key findings and the implication of impropriety.
"People in senior positions have no influence over the decision (to award a contract). The decisions are made by career procurement officials," Boucher told reporters.
"There's a separation, a wall, between them and political-level questions when they're doing the contracts, and the contracts are evaluated for technical merit as well as for the lowest cost."
Contrary to the report, key Iraq contracts were open to competitive bidding, he added.
For example, 10 firms were invited to compete for a contract ultimately awarded to California-based construction giant Bechtel Group Inc. after it and six others vied for the deal, Boucher said.
The contract to restore Iraqi utilities, telecommunications and transport infrastructure, schools and hospitals was valued at just over one billion dollars.
According to the Center report, Bechtel and other contract recipients have been well-connected.
"Nearly every one of the 10 largest contracts awarded for Iraq and Afghanistan went to companies employing former high-ranking government officials or individuals with close ties to those agencies or Congress," the study said.
Bush at another fundraiser in
Georgia earlier this year
"Dozens of lower-profile, but well-connected, companies shared in the reconstruction bounty," it added.
Halliburton Co. - the oil services titan once headed by now Vice President Richard Cheney - scooped up the biggest contract: 2.3 billion dollars for its Kellogg, Brown and Root unit to support the US military and rebuild Iraq's oil infrastructure, the report said.
Halliburton chairman Dave Lesar, responding on Wednesday to lawmakers' allegations the company was overcharging for gasoline imported into Iraq, said criticism of its work there was "less about Halliburton and more about external political issues."
The company won the Iraq contract on the strength of a long track record, not its political connections, he added.
Bechtel chief executive Riley Bechtel serves on the President's Export Council, which advises Bush on trade issues, the report said.
"We do not expect or receive political favors or government contracts as a result of those contributions"
Bechtel website statement
George Schultz, who served as Secretary of State under then president Ronald Reagan in the 1980s, sits on the company's board of directors.
Like Halliburton, Bechtel said its connections had nothing to do with winning contracts.
"We do engage in the political process, as do most companies in the United States," the company said on its website.
"We have legitimate policy interests and positions on matters before Congress, and we express them in many ways, including support for elected officials who support those positions."
"We do not expect or receive political favors or government contracts as a result of those contributions," it added.