Australian Federal Police commissioner Reece Kershaw was contacted by his long-time friend former NSW Police commissioner Mick Fuller, now a partner at PwC, over the unfolding tax scandal.
The consultancy firm's former head of international tax, Peter Collins, is alleged to have improperly used confidential Commonwealth information, with the matter now being investigated by the AFP.
Greens senator David Shoebridge asked Mr Kershaw at a Senate estimates hearing on Thursday whether he had been contacted by Mr Fuller.
Mr Kershaw said he had received a text message from Mr Fuller, who he had known for a number of years.
"He's disappointed with what's occurred, as in the conduct ... of the firm," Mr Kershaw said.
He said he intended to provide a copy of the text message exchange to the committee.
Senator Shoebridge asked the commissioner if Mr Fuller had contacted anyone else at the AFP.
Mr Kershaw said he didn't know, and asked if he should query every employee in the force for clarification.
Senator Shoebridge said in response: "I firmly suggest you have no further contact with Mick Fuller given you're undertaking a police investigation."
Mr Fuller joined PwC as a partner in the firm's consulting business last year.