The claim was made in a congressional report released on Tuesday.
Compiled by Democratic staff of the House Government Reform Committee, the report examined assertions made by Bush, Vice President Dick Cheney, Defence Secretary Donald Rumsfeld, Secretary of State Colin Powell and national security adviser Condoleezza Rice.
The document was requested by California Representative Henry Waxman - the most senior Democrat on the committee and a tenacious critic of some of the contracts awarded to businesses to rebuild Iraq.
"Prior to the war in Iraq, the president and his advisers repeatedly claimed that Iraq possessed weapons of mass destruction that jeopardised the security of the United States.
"The failure to discover these weapons after the war has led to questions about whether the president and his advisers were candid in describing Iraq's threat," the report said.
Most of the statements were misleading because they expressed certainty where none existed or failed to acknowledge the doubts of intelligence officials, according to the report.
Ten statements were just completely false.
Waxman said it demonstrated a "systematic distortion of the intelligence on Iraq," which he said urgently needed investigation.
Condoleezza Rice and Dick Cheney's
public comments were also studied
"Most of the misleading statements about Iraq - 161 statements - were made prior to the start of the war in Iraq.
"But 76 misleading statements were made by the five administration officials after the start of the war to justify the decision to go to war."
White House response
According to the report, the campaign of misinformation began at least a year before the start of the war in Iraq, when Cheney stated on 17 March 2002: "We know they have biological and chemical weapons."
A White House spokesman said he had not yet seen the document and could not comment specifically on its contents.
But despite not having seen the document, the spokesman could still comment: "I can say that the president and his advisers spoke clearly to the American people and the world and their statements accurately reflected the intelligence that was available to them."