The study concluded that the statements "were part of an orchestrated campaign that effectively galvanized public opinion and, in the process, led the nation to war under decidedly false pretenses."
The study was posted Tuesday on the Web site of the Center for Public Integrity, which worked with the Fund for Independence in Journalism.
White House spokesman Scott Stanzel did not comment on the merits of the study Tuesday night but reiterated the administration's position that the world community viewed Iraq's leader, Saddam Hussein, as a threat.
"The actions taken in 2003 were based on the collective judgment of intelligence agencies around the world," Stanzel said.
The study counted 935 false statements in the two-year period. It found that in speeches, briefings, interviews and other venues, Mr. Bush and administration officials stated unequivocally on at least 532 occasions that Iraq had weapons of mass destruction or was trying to produce or obtain them or had links to al Qaeda or both.
"It is now beyond dispute that Iraq did not possess any weapons of mass destruction or have meaningful ties to al Qaeda," according to Charles Lewis and Mark Reading-Smith of the Fund for Independence in Journalism staff members, writing an overview of the study. "In short, the Bush administration led the nation to war on the basis of erroneous information that it methodically propagated and that culminated in military action against Iraq on March 19, 2003."
Named in the study along with Mr. Bush were top officials of the administration during the period studied: Vice President Dick Cheney, national security adviser Condoleezza Rice, Defense Secretary Donald H. Rumsfeld, Secretary of State Colin Powell, Deputy Defense Secretary Paul Wolfowitz and White House press secretaries Ari Fleischer and Scott McClellan.
Mr. Bush led with 259 false statements, 231 about weapons of mass destruction in Iraq and 28 about Iraq's links to al Qaeda, the study found. That was second only to Powell's 244 false statements about weapons of mass destruction in Iraq and 10 about Iraq and al Qaeda.
The center said the study was based on a database created with public statements over the two years beginning on Sept. 11, 2001, and information from more than 25 government reports, books, articles, speeches and interviews.
"The cumulative effect of these false statements - amplified by thousands of news stories and broadcasts - was massive, with the media coverage creating an almost impenetrable din for several critical months in the run-up to war," the study concluded.
"Some journalists - indeed, even some entire news organizations - have since acknowledged that their coverage during those prewar months was far too deferential and uncritical. These mea culpas notwithstanding, much of the wall-to-wall media coverage provided additional, 'independent' validation of the Bush administration's false statements about Iraq," it said.