The US Secretary of State, Mr Colin Powell, has said the United States will not cede control of Iraq to the United Nations after the war.
"We didn't take on this huge burden with our coalition partners not to be able to have a significant dominating control over how it unfolds in the future," Mr Powell told a House of Representatives subcommittee.
"We would not support . . . essentially handing everything over to the UN for someone designated by the UN to suddenly become in charge of this whole operation," he added.
"We have picked on a greater obligation - to make sure there is a functioning Iraqi government that is supported by the coalition, the centre of gravity remaining with the coalition, military and civilian," he said.
But Mr Powell said the United Nations should have a role in a post-Saddam Iraq, if only because it makes it easier for other countries to contribute to reconstruction costs.
"If we ask these nations to go get funds from their parliaments, it makes it a lot easier for them to get those funds and contribute those funds to the reconstruction effort . . . if it has an international standing," he said.
The coalition is the Bush administration's term for the United States, Britain and the other minor contributors to the invasion of Iraq they launched last week.
The question of the UN role has come to the fore in the last few days because of debates in New York on the terms for releasing Iraqi oil money to pay for humanitarian relief.
The problem is expected to loom even larger if the United States takes control in Baghdad and then starts managing the Iraqi oil industry or seeking funds for reconstruction.