It comes as a Legislative Assembly Select Committee prepares to release a report on its inquiry into the scope and powers of a corruption commission in a fortnight.

ACT Policing has been pushing to be exempt from oversight, arguing the existing oversight bodies were sufficient, despite many other witnesses arguing in favour of police coverage.

But in a late supplementary submission to the inquiry, ACT Chief Police Officer Justine Saunders has effectively raised a new, secondary argument, that such oversight could be "legally problematic".

"It is important to note that further oversight of the ACTP may be legally problematic and practically difficult to implement, and our view remains that the current arrangements...provides a high quality of assurance to the government and the community it serves," she said.

While such commissions in other states have powers to investigate corrupt police activity, such powers are being closely considered in the ACT inquiry, as the territory government contracts its police force from the federal government.

The Australian Commission for Law Enforcement Integrity's commissioner Michael Griffin AM told the inquiry if his agency was to report to an Assembly committee, it would require federal legislative changes.

But he said that if such changes were needed to be made, he was "not aware of any reasons that could not work".

The police had not previously raised any legal impediments to commission oversight during hearings or in its original submission.

But an ACT Policing spokeswoman said the submission was sent to address questions on notice and to clarify the police position "on other issues raised".

"ACT Policing has noted that the establishment of a commission would require legal and practical consideration of jurisdictional authority between both ACT and Commonwealth Governments," she said.

The Canberra Times has previously reported on documents released under Freedom of Information laws that raised the prospect of a possible deal between government and the police force on such an exemption.

Neither party has directly answered questions on whether a deal was reached and redactions in the documents released mean it remains an open question.

But Opposition leader Alistair Coe has warned giving police an exemption could "open the door" to other agencies seeking such an exemption and said he remains unconvinced of the merits of the proposal.

CPO Saunders also wrote in the supplementary submission that police continued to support the committee in its work, and was "keen to provide any further clarification" through a "private briefing, if desired", though such a briefing has not occurred to date.

She also repeated an earlier offer of supplying police investigative capabilities to any anti-corruption commission that is created.

"This model successfully reduces and mitigates perceptions about conflict of interest whilst providing high quality investigative services and policing expertise," she wrote.