"There was never a serious debate that I know of within the administration about the imminence of the Iraqi threat," Tenet wrote, according to the newspapers.
Tenet also wrote that he thought that the violence in Iraq was continuing to spiral out of control.
"My fear is that sectarian violence in Iraq has taken on a life of its own and that US forces are becoming more and more irrelevant to the management of that violence," he wrote.
As part of a media tour to promote the book, Tenet was interviewed by the CBS news magazine 60 Minutes, in which he contended that his now-infamous phrase "slam dunk" was taken out of context.
Uttered during a 2002 White House meeting, "slam dunk" was referring broadly to the case that could be made against Saddam Hussein, Tenet argues, and does not apply to the dictator's alleged weapons of mass destruction.
In other news, Tenet accused George Bush's administration of ruining his reputation by misusing the "slam dunk" comment he made during the White House meeting ahead of the US-led invasion of Iraq.
Tenet told CBS Television's "60 Minutes" that the administration leaked his comment as opposition to the war grew when no weapons of mass destruction were found in Iraq.
"You don't do this. You don't throw somebody overboard just because it's a deflection. Is that honourable? It's not honourable to me," Tenet said in an interview to be broadcast on Sunday.
Tenet said his comment did not refer to whether Saddam Hussein had weapons of mass destruction, but related to what information could be used to make a public case for the war.
Tenet, who served under Bush and Bill Clinton, the former president, resigned in July 2004 amid widespread criticism over intelligence lapses. Tenet had been appointed in 1997.
He said the most difficult part was continuing to hear senior administration officials such as Cheney and Condoleezza Rice, US secretary of state, refer to his comment as though they had to hear him "say 'slam dunk' to go to war with Iraq."