U.S. news reports say a memo given to President Bush a month before the September 11 attacks warned that al-Qaida was planning an attack on U.S. soil.
The reports cite people familiar with an intelligence memo delivered to Mr. Bush on August 6, 2001.
The sources say much of the intelligence was uncorroborated, and that the memo did not warn specifically of the September 11 attack.
They say it did warn that al-Qaida was interested in hijacking planes and in carrying out an attack inside the United States using explosives.
The information about the explosives came from a report received by U.S. intelligence in May 2001, three months earlier.
Testifying before the government commission Thursday, the president's national security adviser, Condoleezza Rice, said the memo was "historical" in nature and not a warning of an imminent attack.
The memo -- entitled "Bin Laden Determined To Attack Inside the United States -- is at the center of a debate about whether the Bush administration did enough to deter a terrorist attack before September 11.
A commission investigating the attacks has asked the White House to make the memo public. Administration officials say the memo could be released within days, after they make sure the move will not compromise any intelligence sources.
She also said there was no single thing that could have been done to prevent the attacks, which killed nearly 3,000 people.
President Bush and Vice President Cheney have agreed to meet jointly with the commission in the coming weeks.