Congressional investigators say intelligence agencies had evidence that terrorists might use airplanes to attack targets in the United States, but have found nothing that directly predicted the Sept. 11 attacks, a congressional source said Tuesday.

"We haven't found anything where some part of the government had the information about the where, when and how this attack was going to take place," said the source, speaking on condition of anonymity.

The findings will be part of a report presented Wednesday at the first public hearing of the joint inquiry by the House and Senate intelligence committees. That panel was set up to examine intelligence failures leading up to the attacks last September.

The report will not say outright whether intelligence agencies had enough information to have prevented the attack, said the source. But this person said the report does raise questions about whether the American public was given enough information to understand the likelihood of such an attack.

The report Wednesday will look at what intelligence agencies knew about the likelihood of an attack against U.S. targets in 2001 and about the use of airplanes. A future report will examine what the agencies knew about the 19 hijackers before the attacks.

"This is the beginning. This is not the whole picture," the source said.

Congressional staff members began looking at the attacks early this year. Staff have reviewed some 400,000 documents, about 60,000 to 70,000 of which were considered relevant to the investigation. They have also talked to almost 500 people.

The two committees have held closed-door hearings since early June 4. Open hearings, originally planned for late June, have repeatedly been delayed, largely because of questions about what sensitive documents could be released.

The staff report will be presented by director Eleanor Hill after Wednesday's hearing opens with the appearances of the spouses of two victims of the attacks.

It will address what information U.S. agencies had before Sept. 11 about the likelihood of a domestic attack by international terrorists and about the likelihood of using aircraft as weapons. The report will include details of threats received by the United States, including a surge of reports that peaked in June 2001, then began to fall off.

No public hearings have been scheduled beyond Wednesday. The source said the committees have had difficulty getting the Bush administration to provide witnesses for the public sessions.

Members of the committees have said the administration's lack of cooperation has hindered the inquiry and may prevented it from conducting a thorough review by the time its mandate ends in February. Some have called for a separate, independent investigation, which has been opposed by the administration.