Osama bin Laden kept a handwritten journal that U.S. forces seized in last week's raid, according to an unidentified Associated Press source.

AP correspondent Kimberly Dozier reports that the journal was part of a huge cache of intelligence that included about 100 flash drives and five computers taken by U.S. Navy SEALs after they swept through the bin Laden compound in Abbottabad, Pakistan.

The officials spoke on the condition of anonymity because they were not authorized to talk publicly about what was found in bin Laden's hide-out.

In memoirs, Bin Laden's son Omar has described his father as recording his thoughts and plans when the family lived in Sudan and Afghanistan, the AP reports.

Update at 3:40 p.m. ET: The National Journal's Michael Hirsch, quoting a U.S. official, reports that the handwritten notes are believed to be the terror chieftain's thoughts about future operations and possible targets, along with "musings on al-Qaeda."

The official, described as a U.S. national security team reviewing the vast quantity of material from bin Laden's compound, cautions that while U.S. authorities have not yet confirmed it was bin Laden's diary, "the assumption is that it was."

The official says the journal, and other materials, indicate bin Laden was still very much involved in running al-Qaeda.