Levin told the Senate in plenary session that a CIA letter proved that ahead of the 2001 hijacked-plane attacks on New York and Washington there had been no meeting in Prague between the Hamburg-based lead hijacker Mohammed Atta and an Iraqi spy.

Other records indicated that Atta was "almost certainly in the United States at the time of the purported meeting in Prague," said Levin, who is chairman of the Senate's Armed Services Committee.

He told the Senate late on Thursday that former President George W. Bush and especially Bush's then Vice President Dick Cheney "misled" US citizens ahead of the 2003 invasion by claiming that the September 11, 2001, attacks had a connection with the then Iraqi dictator Saddam Hussein.

"Of course, connections between Saddam and 9/11 or al Qaeda were fiction," Levin said.

Public swayed by misinformation

"There was a concerted campaign on the part of the Bush administration to connect Iraq in the public mind with the horror of the September 11 attacks. That campaign succeeded," said Levin.

He also cited surveys from 2003 that showed that many Americans believed Saddam Hussein was involved in the 9/11 al-Qaeda attacks.

The letter from current CIA director John Brennan released by Levin stated that there was "not one USG (US government counterterrorism) or FBI expert" who had evidence to show that Atta had indeed been in the Czech capital.

"In fact the analysis has been quite the opposite," Brennan wrote.

CIA cable warned against invasion

Levin said he had long sought declassification [publication] of a CIA cable dated March 13, 2003 that warned the then Bush administration against propagating the hijacker-Iraq theory, but to no avail.

Al-Qaeda's Hamburg cell, with Atta (lower middle)

This had followed a December 2001 television appearance by Cheney who claimed that it was "pretty well confirmed" a Prague encounter had taken place between Atta and senior Iraqi agent Ahmad al-Anian months before the hijackers attacked.

Far from Cheney's claim that it was 'pretty well confirmed,' there was "almost no evidence that such a meeting took place," Levin told the Senate, adding that it was an unsubstantiated, "single source" rumor.

Czech agents under pressure

Levin also cited a memoir published early this year by the former head of Czech counterintelligence, Jiri Ruzek, who wrote that US officials had pressured Czech intelligence to confirm that such a meeting had taken place.

Rusek wrote that from a US perspective Czech agents had not provided the "'right intelligence output'."

"They wanted to mine [extract] certainty from unconfirmed suspicion and use it as an excuse for military action," Rusek wrote.

FBI officials quoted by Reuters late on Thursday said Atta was probably in Florida in early April 2001 -- preparing for the September 11 attacks -- and that they had found no evidence of his traveling in Europe around that time.

'False statements'

The conclusion, Levin said, was that future US leaders "must not commit our sons and daughters to battle on the basis of false statements."

The 2003 US-led invasion that toppled Saddam Hussein cost the lives of more than 4,689 soldiers, mostly American, between 2003 and a combat troop withdrawal in 2009.

Civilian deaths in Iraq since 2003 are put at at least 133,000 by the website Iraq Body Count.

Senator Levin's remarks followed the Senate's release of a damning report on CIA interrogations of al Qaeda suspects in the wake of the 9/11 attacks. Al Qaeda hijackers, using four passenger planes, murdered nearly 3,000 people in New York and Washington in the attacks.

ipj/tj (AFP, Reuters, AP)