New York City Metropolitan Transportation Authority spokesman Tom Kelly declined comment.

According to the report, President Bush was shown a model of the weapon in March 2003 and ordered alerts sent through the U.S. government. When intelligence arrived that al-Zawahri had called off the attack, Bush worried that something worse was in the works, Suskind writes.

At least two of Suskind's sources remembered Bush saying, "This is bad enough. What does calling this off say about what else they're planning? ... What could be the bigger operation Zawahri didn't want to mess up?" the author said.

"What has been concluded for the most part is this: al-Qaida's thinking is that a second-wave attack should be more destructive and more disruptive than 9/11," Suskind told the magazine in an interview.

The informant, who had become disgruntled with al-Qaida's leadership, linked the organization's top operative on the Arabian peninsula to the plot, Suskind writes. The operative was later killed in a standoff with Saudi authorities.

The excerpt of Suskind's book, "The One Percent Doctrine," was to appear in Time's issue hitting newsstands Monday. Suskind is a former Pulitzer Prize-winning reporter for The Wall Street Journal.