President George W. Bush and his policymakers misstated Saddam Hussein's links to terrorism and ignored doubts among intelligence agencies about Iraq's arms programmes, the Senate intelligence committee reported today.
The report shows an administration that "led the nation to war on false premises," said the committee's Democratic Chairman, Senator John Rockefeller of West Virginia.
Several Republicans on the committee protested its findings as a "partisan exercise."
The committee studied major speeches by Mr Bush, Vice President Dick Cheney and other officials in advance of the US-led invasion of Iraq in March 2003, and compared key assertions with intelligence available at the time.
Statements that Iraq had a partnership with al-Qaeda were wrong and unsupported by intelligence, the report said.
It said that Mr Bush's and Mr Cheney's assertions that Saddam was prepared to arm terrorist groups with weapons of mass destruction for attacks on the United States contradicted available intelligence.
The report also said administration prewar statements on Iraq's weapons programmes were backed up in most cases by available US intelligence, but that officials failed to reflect internal debate over those findings.
The long-delayed Senate study supported previous reports and findings that the administration's main cases for war - that Iraq had weapons of mass destruction and was spreading them to terrorists - were inaccurate and deeply flawed.
"The president and his advisors undertook a relentless public campaign in the aftermath of the [September 11] attacks to use the war against al-Qaeda as a justification for overthrowing Saddam Hussein," Mr Rockefeller said in written commentary on the report.
"Representing to the American people that the two had an operational partnership and posed a single, indistinguishable threat was fundamentally misleading and led the nation to war on false premises."
A statement to Congress by then-Defense Secretary Donald Rumsfeld that the Iraqi government hid weapons of mass destruction in facilities underground was not backed up by intelligence information, the report said.