By BILL SANDERSON

May 16, 2002 -- Intelligence officials warned President Bush in the weeks before Sept. 11 that Osama bin Laden and his terror henchmen might have been plotting to hijack passenger airliners, the White House said last night.

The warnings, which came in the first 10 days in August, resulted in a secret alert to law enforcement.

But Bush's spokesman said the administration believed bin Laden was merely plotting a "traditional" hijacking.

"There's been a long-standing awareness in the intelligence community, shared with the president, about the potential for bin Laden to have hijackings in a traditional sense," said White House spokesman Ari Fleischer.

"The information the president got dealt with hijackings in the traditional sense - not suicide bombers, not using planes as missiles," he added.

But evidence has surfaced in recent weeks that intelligence and law-enforcement officials had evidence something bigger might have been in the works:

* A classified memo written by a Phoenix FBI agent last summer urged the bureau to investigate a number of Middle Eastern men enrolled in American flight schools, citing bin Laden as someone who could organize such flight training.

* Last August, shortly after the arrest of accused bin Laden terrorist Zacarias Moussaoui, a Minneapolis FBI agent on the case wrote in notes that Moussaoui was the kind of person who might "fly something into the World Trade Center."

* A French investigating judge and terrorist hunter had presented the FBI information weeks before Sept. 11 warning that Moussaoui was a dangerous Islamic extremist.

But nobody in Washington appears to have connected the dots.

Bush and his intelligence experts had no idea any hijackers would be on suicide missions to use the planes as murderous missiles against the World Trade Center and the Pentagon, officials said.

As a result of the information, the administration alerted domestic law-enforcement agencies that hijackings "in the traditional sense" were possible, Fleischer said.

The alert, which was never made public, may have prompted the hijackers to change their tactics, Fleischer said.

The alert was "one of the reasons that you saw that the people who committed the 9/11 attacks used boxcutters and plastic knives to get around America's system of protecting against hijackings," Fleischer said.

Hijackings by al Qaeda terrorists were just one of "many things that we talked about all the time as a potential terrorist threat," said a U.S. intelligence official, speaking on condition of anonymity.

"But when we talked about hijackings, we talked about that in the traditional sense of hijackings, not in the sense of somebody hijacking an aircraft and flying it into a building," the intelligence official said.

"We talked about concern about the general noise level about al Qaeda planning, and we were trying to figure out what they would do. We never had specifics about time, place, MO [method of operation]."

Congressional investigators are focusing on why the FBI failed to put the different information about the threats together.

Sen. Richard Shelby (R-Ala.), a member of the Senate Intelligence Committee, said the Phoenix FBI memo "was a very important warning and it was not heeded. It was not distributed. It was not acted on."

With Post Wire Services