US intelligence 'knew of hijackers' links with al-Qa'ida before 11 September attacks'

America's National Security Agency intercepted conversations in 1999 indicating that two of the hijackers involved in the 11 September attacks had direct links to al-Qa'ida, but it failed to pass the information on to other American intelligence agencies, a report published yesterday shows.

The revelation is buried deep within the 900-page congressional report on the lapses in American security that may have contributed to the failure to pre-empt the attacks on New York and the Pentagon in 2001.

The report, parts of which are still being censored, is reviving political debate over how much blame should be attributed to the main intelligence agencies - the NSA, the Central Intelligence Agency and the Federal Bureau of Investigation.

The report did not appear to single out a "smoking gun" event indicating a single mistake on which the intelligence break-down could be pinned.

But Senator Bob Graham, a Florida Democrat who is running for president, said the report exposed serial mistakes. When asked in a television interview yesterday if he thought the attacks could have been prevented without the errors, he said: "Probably, yes."

He told CNN: "Unfortunately, there's a lot of blame to be spread around. If there had been more co-operation and sharing of information, if there had been more creativity, and some luck, this plot could have been discovered well before it resulted in 11 September."

The picture might seem more bleak, Senator Graham added, if the public was given access to the missing parts of the report. "The most significant sets of events, in my opinion, are in the section of the report that has been censored and therefore won't be available to the American people," he said.

Particular criticism is reserved for the NSA, which in 1999 successfully intercepted conversations tying two of the hijackers, Khalid al-Mihdar and Nawaf al-Hazmi, to Osama bin Laden's terror network, al-Qa'ida. But it failed to pass on the intelligence to the FBI or the CIA until early 2002, after the attacks had happened. Both men were on the plane that crashed into the Pentagon.

The report says the CIA did learn independently of the links between the men and the terror group in early 2000 but the agency did not put the pair on its anti-terror lists. This meant they were able to enter the US unimpeded. After their arrival, moreover, they lived in San Diego with a man who was an undercover FBI informant. Yet nothing was done to have the informant monitor their activities.

The report noted: "As a result, the FBI missed the opportunity to task a uniquely well-positioned informant - who denies having any advance knowledge of the plot - to collect information about the hijackers and their plans in the United States."

The congressional investigation also ascertained that the National Security Agency intercepted "some communications that indicated possible impending terrorist activity" between 8 September and 10 September, but these were not disseminated to anyone until after the attacks.

The White House said steps had already been taken to improve communications between intelligence agencies. The focus on protecting US shores from terrorists was also at the forefront of President George Bush's decision to consolidate government departments into the Department of Homeland Security.

Scott McClellan, a White House spokesman, said the report "confirms the importance of the strong, aggressive stance we have already taken".

But some Republicans played down any notion that the events of 11 September could have been preventedwith better intelligence. Ray LaHood, a Republican congressman said: "Anybody who makes an assertion that this could have been prevented is making a political statement because there is no information that was shared with the top people in our government that could have led them to believe this was going to happen. It wasn't there."