Former FBI agent says truth of 9/11 remains hidden
12 September 2011 Last updated at 22:24 BST
A former FBI agent has told the BBC that he is being prevented from telling the truth about the events of 9/11 and what has happened since.
Ali Soufan alleges that crucial intelligence was not passed on from the CIA before the attacks in 2001.
He has written a book detailing some of his claims and has been speaking to the BBC's Security Correspondent Gordon Corera in his first on camera interview on the subject.
In response to the allegations in this report the CIA issued a statement to the BBC that said: "Any suggestion that the CIA purposely refused to share critical lead information on the 9/11 plots with the FBI is baseless."
"The suggestion that the Central Intelligence Agency has requested redactions on this publication because it does not like the content is ridiculous."
The CIA decline to comment on the record about the accusations regarding waterboarding and interrogation.