Investigators have found no "credible evidence" Iraq aided al Qaeda attempts to strike the US, a commission investigating the September 11th, 2001, attacks said this evening in a report that significantly undermines Bush administration arguments for war.
The statement was published before the bipartisan commission began the final two-day public session.
The report said al Qaeda leader Osama bin Laden had met with a senior Iraqi intelligence officer in 1994 and had explored the possibility of co-operation, but the plans apparently never came to fruition.
Statement from September 11 Commission
US President George W. Bush and Vice President Dick Cheney this week reiterated pre-war arguments that an Iraqi connection to al Qaeda, which is blamed for the September 11th attacks, represented an unacceptable threat.
This contradicts comments by the US vice-president, Mr Cheney who claimed Saddam Hussein had "long-established ties" with al-Qaeda.
However, the commission said in a staff report: "We have no credible evidence that Iraq and al Qaeda co-operated on attacks against the United States."
"There is no convincing evidence that any government financially supported al Qaeda before 9/11 - other than limited support provided by the Taliban after bin Laden first arrived in Afghanistan," it added.
Counterterrorism officials from the FBI and CIA testifying at Wednesday's hearing said they agreed with the staff report's conclusion.
The report was issued at the start of the commission's final two days of public hearings into the hijacked-plane attacks, which killed nearly 3,000 people.
The hearings were called to find out how the United States failed to prevent the attacks and what it can do now to improve security.
Mr Bush, asked yesterday about Mr Cheney's comments, cited the presence in Iraq of Islamist militant Abu Musab al-Zarqawi as "the best evidence" of an Iraqi connection to al Qaeda.
The president maintained today Saddam had "sheltered terrorist groups" and America was safer because of his ousting.
Although Mr Cheney and other officials had suggested Iraq might have played a direct role in the September 11th attacks, Mr Bush acknowledged after the war that there was no evidence of this.