American President George Bush and top US officials made a total of 935 false statements in the run-up to the Iraq war, according to a damning report by US researchers.
The statements, that mentioned Iraq's weapons of mass destruction or links to al-Qaeda, were part of a deliberate campaign to spread "erroneous information", the Centre for Public Integrity report said.
"Bush and seven of his administration's top officials methodically propagated erroneous information over the two years beginning on September 11, 2001," the group said on Wednesday.
Bush made 260 false statements and Colin Powell, his then secretary of state, 254, the study said.
"These false statements dramatically increased in August 2002, just prior to congressional consideration of a war resolution and during the critical weeks in early 2003," the report added.
This was the period when the president "delivered his State of the Union address and Powell delivered his memorable presentation to the UN Security Council," the group said.
The group has also published a searchable database of all the Bush administration's statements during the period on its website.
The White House alleged that Saddam Hussein, the former Iraqi leader, had stockpiled an arsenal of weapons of mass destruction.
This was used as the main argument by the US and it allies over the war to justify the US-led invasion.
But after the invasion they turned out to be untrue, when no weapons of mass destruction were found by invading forces.
"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.
Dick Cheney, the US vice-president, made 48 false statements in the run-up to the war, the group said.
Condoleezza Rice, who was at that time national security adviser, Donald Rumsfeld, then defence secretary, and Paul Wolfowitz, ex-deputy defence secretary, were also criticised in the study,
The statements of Ari Fleisher and Scott McClellan, both former White House press secretaries, were also targeted by the report.
"This is a report like no other, which calls into question more than 900 false statements that were the underpinnings of the administration's case for war," said Bill Buzenberg, the CPI's executive director.
In late September 2002, ahead of a congressional vote authorising the use of military force in Iraq, Bush insisted in a radio address that the Baghdad government posed a global threat.
"The Iraqi regime possesses biological and chemical weapons, is rebuilding the facilities to make more and, according to the British government, could launch a biological or chemical attack in as little as 45 minutes after the order is given," Bush said.
Other administration officials made false statement on the alleged relationship between Iraq and the al-Qaeda network, the CPI said. Asked in July 2002 if Iraq had relationships with al-Qaeda, Rumsfeld said: "Sure."
However, an assessment the same month by the Defense Intelligence Agency, confirmed later by George Tenet, the then CIA chief, found an absence of any "compelling evidence demonstrating direct co-operation between the government of Iraq and al-Qaeda."