The nation's top cop has been accused of failing to declare a conflict of interest, after documents produced to the Senate showed he met multiple times with a "friend" who now worked for consulting firm PwC over a contract awarded without public tender.

Greens senator David Shoebridge told the Senate documents handed over by the government showed Australian Federal Police commissioner Reece Kershaw had a closer involvement in designing a $750,000 contract for PwC than previously suggested.

The documents detailed five meetings in the back half of 2022 between Mr Kershaw and former NSW police commissioner Mick Fuller, a friend of Mr Kershaw who last year joined PwC as a partner in government relations.

The meetings included one before the contract was awarded.

Senator Shoebridge told the Senate it exposed "intimate" involvement by Mr Kershaw in designing the contract offered to PwC without a public tender process.

"We now know from the documents that have been produced that commissioner Kershaw actually attended a meeting on the 28th of July 2022, with his mate Mick Fuller, and it was described as, 'An introductory meeting to outline the identified need to undertake an comprehensive independent review of the AFP's delivery of policing services to the ACT government'," Senator Shoebridge read to the Senate.

"And, get this, 'This informed PwC's consideration of whether they had the ability to undertake the work, and would submit a formal quote'.

"The meeting of course was not minuted. So two mates get together ... in an un-minuted meeting, to work out how PwC can get money from the AFP."

In a statement, a spokesperson for the AFP says it "categorically rejects the assertions made", and referred to comments the commissioner made at Senate estimates last month.

Mr Kershaw said last month Mr Fuller had been chosen as the reviewer because the AFP needed someone with "the requisite policing experience" to undertake the review, and noted that he did not personally sign the contract.

Federal police are investigating a former PwC executive who allegedly provided confidential information to assist clients to avoid a planned tax being introduced by the government.

A parliamentary committee found on Tuesday PwC had monetised confidential information in "a calculated breach of trust", which it then deliberately sought to cover up.

Shoebridge challenges testimony given by Kershaw

In estimates hearings last month, Mr Kershaw said he had not declared a conflict of interest over his friendship with Mr Fuller, adding he had received only one text message from Mr Fuller since the scandal broke.

Mr Kershaw said in that message Mr Fuller had described his "disappointment" in the firm.

The text exchange, now disclosed to the Senate, read:

Mick Fuller: Just saw news re referral. Will give you some space so not too complicate your life

Reece Kershaw: Ok thx mate

In another text exchange two weeks before their initial meeting, Mr Fuller said he would call in advance "if okay", to which Mr Kershaw responded "good plan".

Senator Shoebridge said those exchanges differed to what Mr Kershaw had told the Senate, and that conflict-of-interest concerns demanded further investigation.

"This is PwC using its mates, inveigling itself into — in this case — the heart of the Australian Federal Police, manipulating those contracts and those mateships to actually form the contract without a tender, without any public discussion, and suck in another quick three quarters of a million dollars out of the public purse," Senator Shoebridge told the Senate.

He said it was concerning that the same agency "hobnobbing" with PwC partners was now investigating the firm over alleged confidentiality breaches.

"Where is the conflict of interest form from the federal police commissioner? And without that clear statement about conflict of interest, how can we have confidence in the Australian Federal Police's investigation of PwC?" Senator Shoebridge asked.

Mr Kershaw said in May he had "utmost confidence" the right systems were in place within the force to avoid a conflict of interest.

The AFP will return for further questioning at a spill-over estimates hearing next month.