Stuart Kuttner said he had “no recollection” about emails he sent Surrey Police about messages on Milly Dowler’s phone in April 2002, a court heard.
The Old Bailey heard transcripts from several police interviews Kuttner gave officers while investigating phone-hacking claims.
During one interview in September 2011, the 73 year-old former News of the World managing editor said he had “absolutely nothing to hide”.
He insisted however, that he could not speculate on the contents of the message.
During the interview, one detective told Kuttner: “In that letter it clearly stipulates that News of the World, ie yourself and others, potentially have knowledge of messages being left on Milly Dowler's phone and the content of such messages."
Kuttner told officer in interview: "I am not denying, although I have no recollection of the letter, I am not denying its contents."
The detective urged Kuttner to read through the letter, stating: "I don't want you to speculate – I'm asking you to read through a letter you have written and I want you to tell me whether or not you agree with my submission that this is you saying that you know that Milly Dowler's phone has been hacked."
Kuttner replied that "I do not believe that a speculation by me on a letter I do not recall" would be helpful.
He later added that he has never "to the best of my knowledge" had any dealing with private investigator Glenn Mulcaire.
"Whether Glenn Mulcaire provided information to someone at the News of the World which was directly or indirectly passed to me for passing to the police, I cannot say – that is back to the area of speculation," Kuttner said.
During questioning, Kuttner later stated: " If, and I've no reason to doubt this at all, if Milly Dowler's messages were intercepted – and I'm no expert in the law – I quite accept that that was an illegal activity."
He added that it "is clear from the letter that the paper has information".
Kuttner, 73, of Woodford Green, Essex, and the tabloid's former editor Andy Coulson (pictured above Credit: Reuters) are accused of conspiring to hack phones between 3 October 2000, and 9 August 2006, along with former News International chief executive Rebekah Brooks.
Former News of the World and Sun editor Brooks also faces two counts of conspiring with others to commit misconduct in public office – one between 1 January 2004 and 31 January 2012, and the other between 9 February 2006, and 16 October 2008 – linked to alleged inappropriate payments to public officials.
She also faces two allegations of conspiracy to pervert the course of justice – one with her former personal assistant Cheryl Carter, 49, of Chelmsford, Essex, between 6-9 July 2011, and a second with her husband, Charles Brooks, and former News International head of security Mark Hanna and others between 15-19 July 2011.
Coulson is also facing two allegations that he conspired with former NotW royal editor Clive Goodman, 56, from Addlestone in Surrey, and other unknown people to commit misconduct in public office between 31 August 2002 and 31 January 2003, and between 31 January and 3 June 2005.
Jurors were told that news editor Ian Edmondson, who is charged with conspiring to hack phones between 3 October 2000 and 9 August 2006, is ''currently unfit'' and will take no further part in the trial.
In May 2012 Kuttner made a statement to police denying the allegations and stating he was not willing to answer any further questions.
Kuttner described the note as a " a letter of cooperation".
The jury was told that Kuttner made the statement in May 2012 while under arrest and being questioned by police for the fifth time.
He told the detectives during his police interview: "As I have already said to my great shock and distress over long gruelling and exhaustive session, you have accused me of consipiring to intercept messages and conspiring to corrupt police.
"Again, as I have said on a previous occasion, I have striven to maintain and improve standards in our industry, to support and liaise with police on countless occasions and to uphold the reputation of newspapers I have worked for.
"Now at the age of 72, three years into my retirement and coping with heart attacks and the effects of a brain stem stroke, including permanent distorted eyesight, I have been plunged into a nightmare."
He said he had tried to be helpful but "I now find the pressure of this intensive police activity to be intolerable".
He said: "Last year I told you I have never knowingly, intentionally or otherwise, conspired with anyone to carry out any unlawful acts whatsoever. Allegations or suggestions to the contrary are unfounded and false – that remains the situation."
Kuttner later sent a note to the police about the April 2002 letter in which he stated: "For completeness and clarity, I wish to add to what I said on the last occasion regarding that document.
"I have no memory of it at all. I am unable to recall the circumstances or who provided me with the information contained in that communication and I do not believe it is helpful or right to speculate.
"Unless I have the opportunity to look into the circumstances in which I came to write the email, I am unable to assist further at this stage."
All of the defendants deny all of the charges.
The trial continues.