Former News International chief executive Rebekah Brooks has admitted paying public officials for information on "half a dozen" occasions during her time as a newspaper editor.
But she denied knowing that a source paid by the Sun for stories over eight years worked for the Ministry of Defence (MoD).
Mrs Brooks, 45, told the phone hacking trial at the Old Bailey she sanctioned payments on "a handful" of occasions between 1998 and 2009, when she edited the News of the World (NotW) and later the Sun. Asked by her lawyer Jonathan Laidlaw QC if she ever sanctioned payments to public officials, Brooks answered: "Yes."
Questioned on how many times, she replied: "A handful of occasions - half a dozen. My view at the time was that there had to be an overwhelming public interest to justify payments in the very narrow circumstances of a public official being paid for information directly in line with their jobs."
The court has previously heard claims that MoD press officer Bettina Jordan-Barber received a total of £100,000 for information she provided to the Sun.
Mrs Brooks said she did not know Ms Jordan-Barber was providing information to one of the newspaper's journalists, who cannot be named, or that Ms Jordan-Barber worked as a public official.
"He never told me any of his confidential sources," Mrs Brooks said.
"I mean most journalists kept their contacts and sources pretty close to their chest."
Mrs Brooks, of Churchill, Oxfordshire, denies conspiring with others to commit misconduct in public office between January 1, 2004 and January 31, 2012. She also denies conspiring to hack phones and cover up evidence to pervert the course of justice.
The trial continues.