WASHINGTON -- President Bush's August 2001 briefing on terrorism threats, described largely as a historical document, included information from three months earlier that al-Qaida was trying to send operatives into the United States for an explosives attack, according to several people who have seen the memo.

The so-called presidential daily briefing, or PDB, delivered to Bush on Aug. 6, 2001 -- a month before the Sept. 11, 2001, attacks -- said there were various reports that Osama bin Laden had wanted to strike inside the United States as early as 1997 and continuing into the spring of 2001, the sources told The Associated Press.

The same month as that briefing of Bush, U.S. intelligence officials received two uncorroborated reports suggesting terrorists might use airplanes, including one that suggested al-Qaida operatives were considering flying a plane into a U.S. embassy, current and former government officials said.

Those August 2001 reports -- among thousands of varied and uncorroborated threats received by the government each month -- weren't deemed credible enough to tell the president or his national security adviser, Condoleezza Rice, the officials said. Neither involved the eventual Sept. 11 plot.

Classified report

The sources who read the presidential memo would only speak on condition of anonymity because the White House has not yet declassified the highly sensitive document, entitled "Bin Laden Determined to Strike Inside the United States."

That declassification process is expected to be completed soon, allowing the Bush administration to make the document public in a historic disclosure of secret presidential intelligence briefing materials.

The sources said the presidential memo included a series of bullet items that brought Bush through a history of mostly uncorroborated intelligence that cited al-Qaida's interest in hijacking planes to win the release of Islamic extremists who had been arrested in 1998 and 1999 as well as the travelings of suspected al-Qaida operatives, include some U.S. citizens, in and out of the United States. It suggested al-Qaida might have a support system in place on U.S. soil, the sources said.

The document also included FBI analytical judgments that some al-Qaida activities were consistent with preparation for airline hijackings or other types of attacks, some members of the Sept. 11 commission said earlier this week.

The second-to-last bullet told the president that there were numerous -- at least 70 -- terror-related investigations under way by the FBI in 2001 involving matters or people on U.S. soil, the sources said.

And the final bullet told the president of a recent intelligence report indicating al-Qaida operatives were trying to get inside the United States to carry out an attack with explosives, the sources said. There was no specifics about the timing or target, the sources said.

The sources said the briefing memo did not provide the exact date of that intelligence but made clear it was in the 2001 time frame, and that FBI and other agencies were investigating it. The information had been provided to intelligence and law enforcement agencies well before Bush's briefing, the sources said.

They said final bullet in the presidential memo was based on an intelligence report received in May 2001 that indicated bin Laden operatives were trying to cross from Canada into the United States for an attack.

A joint congressional inquiry report into the Sept. 11 failures first divulged the existence of the May 2001 threat report last year but did not reveal it was included in Bush's briefing. The congressional inquiry described the intelligence this way:

"In May 2001, the Intelligence Community obtained information that supporters of Osama bin Laden were reportedly planning to infiltrate the United States via Canada in order to carry out a terrorist operation using high explosives."