By Martin HickmanA Sun journalist was briefed by a member of Britain's domestic counter-intelligence and security agency MI5, it was suggested at the hacking trial today.In an email read to the Old Bailey, the reporter told the paper's editor, Rebekah Brooks (then Wade), he had received information from “5".On 6 January 2009 he sent the email to Mrs Brooks and copied in her then deputy (and later Sun editor) Dominic Mohan and Trevor Kavanagh, The Sun's political commentator.The Sun reporter - who cannot be named for legal reasons - wrote: "Just heard back from my man at 5.”Later in the email, he stated that "the spooks" were keeping an open mind about possible security problems in the UK arising from the situation in Gaza.Jonathan Laidlaw, QC, for Mrs Brooks, raised the issue of who might have briefed the journalist while cross-examining a police officer about the Crown's allegation that Mrs Brooks committed misconduct in public office by authorising payments to a Defence official.During earlier evidence Mr Laidlaw suggested there may have been alternative sources of information for stories about defence matters which had appeared in The Sun during Mrs Brooks's editorship.He asked Detective Constable Jim Briddon, from Operation Elveden, the Metropolitan Police's inquiry into corruption of public officials: "Is that do you think a reference to someone at MI5, the security service?” Det Const Briddon replied: "I believe that could be the case."Mr Laidlaw pressed: "Is there any evidence of any payment you found to anyone working at the security agency?” Det Const Briddon replied: "Not that we could find."Mrs Brooks and her co-defendants have pleaded not guilty to all charges. The case continues.