WASHINGTON, July 24: The Sept 11, 2001, attacks may have been prevented had US security agencies shared and acted upon information they already had, a US congressional panel concluded in a report made public on Thursday.

“No one will ever know what might have happened had more connections been drawn between these disparate pieces of information,” the report said.

The long-awaited report also said Saudi Arabia may have played a critical role in the devastating assault.

It concluded that there was “no smoking gun” — no single source of information that might have allowed US authorities to uncover and prevent the plot.

But the 900-page document noted that “within the huge volume of intelligence reporting that was available prior to Sept 11, there were various threads and pieces of information that, at least in retrospect, are both relevant and significant”.

Th document said that in the three years up to the attacks, US intelligence agencies had reports that Osama bin Laden’s followers planned to hijack aircraft, attack US targets and had staged a “dry run” at a New York airport.

The final 900-page report included newly declassified details from the joint inquiry of the House of Representatives and Senate intelligence committees conducted last year.

A section on whether there was any Saudi support for the hijackers remained classified except for one page.

Congressional sources said there was no conclusion that some people who came in contact with two of the hijackers in San Diego had acted on behalf of the Saudi government, but added that issue needed to be aggressively investigated.

The one page that was declassified in that section said: “Through its investigation, the joint inquiry developed information suggesting specific sources of foreign support for some of the Sept 11 hijackers while they were in the United States.”

The report also said US government officials had complained before the Sept 11 attacks that Saudi Arabia was uncooperative on issues relating to terrorism and Osama bin Laden.

“A high-level US government officer cited greater Saudi cooperation when asked how the Sept 11 attacks might have been prevented,” the report said. “In May 2001, the US government became aware that an individual in Saudi Arabia was in contact with a senior Al Qaeda operative and was most likely aware of an upcoming Al Qaeda operation,” the report said.

FBI INFORMANT: The report details the contacts of an FBI informant with two of the Sept 11 hijackers, Khalid al Mihdhar and Nawaf al Hazmi, while they were living in San Diego.