Atta: Thought to be in Florida at time of alleged meeting

Last year, US and Czech officials said that the chief hijacker, Mohammed Atta, had met an Iraqi agent in Prague.

But now US investigators have said that there is not even evidence to show that Atta had been in Prague at the time of the alleged meeting.

The news comes as the FBI admits it has failed to unearth any paper trail leading to the 11 September attacks.

Czech denial

According to a Newsweek report, the Czechs acknowledged several months ago that they may have been mistaken about the whole affair.

I believe the intelligence services more than journalists

Czech interior minister

"Neither we nor the Czechs nor anybody else has any information he was coming or going [to Prague] at that time," said a US official quoted by Newsweek.

Atta is known to have been in Prague in June 2000, but investigations indicate that at the time of the alleged meeting with the Iraqi agent, Ahmed Chalil Ibrahim Samir Ani, in April 2001, he was in Virginia Beach and Florida.

The Czech Interior Minister, Stanislav Gross, however, insists there is no reason to doubt the initial reports of the meeting.

"At present I don't have the slightest information that the reports I received from the intelligence service were not in order. I believe the intelligence services more than journalists," he told the Czech press agency, CTK.

The meeting was considered an indication of Iraq's complicity in planning al-Qaeda attacks and the admission that it cannot be substantiated is seen as a blow to US attempts to build a case against Iraq as a terrorist threat.

Witness 'unlawfully detained'

In a separate development, the US investigation suffered another setback when a federal judge declared that a Jordanian student, held in connection with the 11 September attacks, had been detained unlawfully.

Awadallah: Says he was questioned without a lawyer

Judge Shira Scheindlin ruled testimony by Osama Awadallah to a grand jury about the hijackers could not be used because the government had abused the material witness statute - a law allowing witnesses to be detained - in arresting him.

The decision could have wide-ranging implications for the US crackdown on terrorism, as dozens of potential witnesses have been jailed by investigators under the statute.

Mr Awadallah was detained on 20 September after his phone number was found in a car abandoned by the hijackers at Washington's Dulles airport.

He alleges 20 FBI agents had surrounded him, did not advise him of his rights and questioned him without a lawyer.

"Relying on the material witness statute to detain people who are presumed innocent under our Constitution in order to prevent potential crimes is an illegitimate use of the statute," Ms Scheindlin said.

Investigations run cold

But US Attorney General John Ashcroft rejected the ruling, describing it as an "anomaly", and said it would not jeopardise the investigations.

"The department's use of material witness warrants is fully consistent with the law and longstanding practice," he said.

The investigations into the planning and execution of the 11 September attacks on New York and Washington have so far borne little fruit.

The FBI has admitted that despite seven months of investigations chasing hundreds of thousands of leads, they have found no hard evidence mentioning the attacks.

FBI Director Robert Mueller said the attackers hid communications by using pay and mobile phones and stored nothing on computer.