His comments come just a week after a survey showed nearly 70% of Americans believe the Iraqi president was connected to the hijacked plane attacks two years ago.
"We have no evidence that Saddam Hussein was involved with the September 11 attacks," Bush told journalists as he met members of Congress on Wednesday.
However, the US president insisted Saddam had links to al-Qaida, the group the US blames for plotting and carrying out the 2001 attacks.
Most political analysts both in the West and the Arab world dispute that Saddam Hussein, an avowed secularist, ever had meaningful links to al-Qaida, a radical Islamist group opposed to his Baathist regime.
Critics have said Washington’s repetition of this claim has created confusion in the minds of most Americans. According to a recent Washington Post poll, 69% of Americans believe Saddam probably had a role in attacking the US.
President George Bush insists
Saddam has links to al-Qaida
Many also believe at least some of the 9/11 hijackers were Iraqi – none of the men identified by the US authorities was from Iraq.
Critics have said the Bush administration sowed this confusion deliberately to win public support for attacking Iraq and toppling Saddam Hussein last spring.
Democratic senators have also accused the White House of feeding public confusion by mentioning Hussein and the 11 September attacks in ways that suggest a link.
Bush himself has recently taken to referring to Iraq as “the central front in the war against terror” and his administration has suggested al-Qaida operatives are active in Iraq. Critics say there is no proof of this either.
Vice President Dick Cheney recently clouded the issue of links between Saddam and the 9/11 attacks during a nationally televised interview on Sunday.
Vice President Dick Cheney (R)
with the US defence secretary
“It’s not surprising people make that connection,” he told NBC's Meet the Press programme.
"We learned more and more that there was a relationship between Iraq and al-Qaida that stretched back through most of the decade of the 1990s.”
Cheny also revived claims of an alleged meeting in April 2001 between suspected 9/11 hijacker Mohamed Atta and an Iraqi agent – a meeting that US intelligence sources say is unproved. The US Central Intelligence Agency reported to Congress last year it could not substantiate the claim.
The Boston Globe newspaper on Tuesday quoted a former CIA counter-terrorism specialist, Vincent Cannistraro, as saying Cheney's "willingness to use speculation and conjecture as facts in public presentations is appalling. It's astounding."