Chief police officer Neil Gaughan emailed ACT Policing members on Thursday, when he says a media enquiry made him aware Director of Public Prosecutions Shane Drumgold SC had released correspondence between the pair under freedom of information laws.

The correspondence was a letter the top cop had received from Mr Drumgold, who made explosive claims police had been "clearly aligned" with Bruce Lehrmann, the man who denies raping Brittany Higgins at Parliament House, rather than the prosecution.

Mr Drumgold also alleged he had been pressured by investigators not to prosecute Mr Lehrmann, whose trial was aborted because of juror misconduct, adding that Ms Higgins had even felt "bullied" by investigators to drop her rape complaint.

In his email, seen by The Canberra Times, Deputy Commissioner Gaughan told members "ACT Policing was not consulted in the [freedom of information] process".

It is understood Mr Drumgold's letter, which contained the personal details of some officers involved in the investigation, was not redacted prior to its release to the Guardian.

"Let me be clear, the allegations the DPP has made against individual ACT Policing members are untested," Deputy Commissioner Gaughan wrote in his message.

"These allegations are being dealt with through the appropriate mechanisms, so I am unable to comment further."

The police chief added that Mr Drumgold had raised a view that there should be a public inquiry into "political and police conduct during the investigation and trial of this matter".

"I welcome a public enquiry [sic] into all aspects of the matter," he told his staff.

Deputy Commissioner Gaughan said Operation Covina, the investigation into the alleged rape, had been "a challenging case for all involved", acknowledging the "dedication, professionalism and commitment of the officers involved".

"I ask that you deal with this in the same manner," he told ACT Policing members.

"I also ask that you look out for each other and if you have concerns raise them with your leaders and with the executive."

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ACT Attorney-General Shane Rattenbury described Mr Drumgold's letter as "extremely concerning" on Friday morning, though he seemed to later resile from those remarks when he told The Canberra Times "professional difference is an acceptable situation".

Asked whether the seemingly strained relationship between police and the office that prosecutes on their behalf was tenable, Mr Rattenbury replied: "I'd encourage the community to look at the broader relationship between [ACT] Policing and the DPP, and to not focus solely on this individual matter".

The police handling of Mr Lehrmann's case has been referred to the Australian Commission for Law Enforcement Integrity following Mr Drumgold's concerns being raised.

Notwithstanding the evident tensions between the agencies, Deputy Commissioner Gaughan encouraged police to maintain a good relationship with Mr Drumgold's office.

"My expectation is that ACT Policing will continue to actively engage with the ACT DPP and his officers to ensure this relationship is as strong as possible," he wrote in his email.

"Without this proper justice and the community cannot be served."

Mr Drumgold has declined to comment on the matter, other than to confirm he was aware his letter had been released to the Guardian under freedom of information laws.