The White House acknowledged Wednesday night that U.S. intelligence agents warned President Bush a month before Sept. 11 that Usama bin Laden's terror network might hijack American planes, but officials said the president had no way of knowing that they would use the planes as missiles for suicide attacks on American landmarks.

"There has been long-standing speculation, shared with the president, about the potential of hijackings in the traditional sense," White House press secretary Ari Fleischer said. "We had general threats involving Usama bin Laden around the world and including in the United States."

He said the administration, acting on the information received in early August, notified the "appropriate agencies" that hijackings "in the traditional sense" were possible. The warning was never made public, he said.

The development, first reported by CBS News, comes as congressional investigators intensify their study of whether the government failed to adequately respond to warnings before Sept. 11. It is the first direct link between Bush and intelligence gathered before Sept. 11 about the attacks on the World Trade Center and the Pentagon.

Fleischer would not discuss when or how the information was given to Bush, but a senior administration official, speaking on condition of anonymity, said the president was made aware of the potential for hijackings of U.S. planes during one or more routine intelligence briefings last summer.

The CIA would not confirm what it told Bush, but the agency said the issue of bin Laden's attempting an airline hijacking was among a number of terrorist methods raised to U.S. government officials at the time.

But there was no information that suggested hijackers would crash planes into American landmarks and there was no mention of a date, a CIA official said.

The information was based on intelligence obtained by the U.S. government, the official said, without specifying.

"I will tell you there was, of course, a general awareness of Usama bin Laden and threats around the world, including the United States; and if you recall, last summer we publicly alerted and gave a warning about potential threats on the Arabian peninsula," Fleischer said.

But he said Bush never had been told about the potential for suicide hijackers steering the planes toward U.S targets.

Still, acting on the information the government did have, the administration "notified the appropriate agencies. I think that's one of the reasons that we saw the people who committed the 9/11 attacks used box cutters and plastic knives to get around America's system of protecting against hijackers," he said.

Fleischer said he did not know what agencies were notified, what they were told or what they did in response.

The Associated Press reported earlier this month that FBI headquarters did not act on a memo last July from its Arizona office warning there were a large number of Arabs seeking pilot, security and airport operations training at at least one U.S. flight school and which urged a check of all flight schools to identify more possible Middle Eastern students.

A section of that classified memo also makes a passing reference to bin Laden, speculating that Al Qaeda and other such groups could organize such flight training, officials said. The officials said, however, that the memo offered no evidence bin Laden was behind the students that raised the concern.

Sen. Bob Graham, D-Fla., the Senate Intelligence Committee chairman, said through a spokesman Wednesday that the revelations in the memos marked an important discovery in Congress' investigation into why the FBI, CIA and other U.S. agencies failed to learn of and prevent the Sept. 11 plot.

"It represents a failure to connect the dots," Graham spokesman Paul Anderson said. "This was dismissed rather lightly at FBI headquarters."

The FBI also has faced tough questioning about whether it failed to act aggressively enough after arresting Zacarias Moussaoui, a Frenchman of Moroccan descent, in August after he raised concerns by seeking flight training at a Minnesota flight school.

Moussaoui has emerged as the lone defendant charged in the aftermath of the attacks, which killed more than 3,000 people in New York, Washington and Pennsylvania. He is charged with conspiring with bin Laden and the 19 suicide hijackers to attack Americans.

FBI Director Robert Mueller repeatedly has said he wished the FBI had acted more aggressively in addressing the Arizona and Minnesota leads but said nothing the FBI possessed before Sept. 11 pointed to the multiple-airliner hijacking plot.

The Associated Press contributed to this report.