Kevin Burrowes told a Senate inquiry the global firm was unable to hand over key details from a 2023 report by law firm Linklaters, which cleared overseas partners from using confidential Treasury information for commercial gain.
Six PwC executives were disciplined for not asking enough questions about the breach, the report found.
Senator Barbara Pocock called Mr Burrowes 'a patsy' for PwC and said he'd been hung out to dry. (Lukas Coch/AAP PHOTOS)
Despite requests to PwC's international office to hand over the report, those requests were rejected, Mr Burrowes said.
"I've formally requested that report again from PwC International Limited and that request was refused on the basis that the information contained in that report is privileged and confidential to PwC," he told a Senate hearing on Friday.
Liberal committee chair Richard Colbeck scolded the consulting boss, saying Mr Burrowes was being "hamstrung" by PwC's international arm.
"I can't in any good conscience acknowledge that I have confidence when your organisation, and you are part of that organisation, is thumbing their nose at our parliament," Senator Colbeck said.
"Don't we at least deserve to understand what the penalties were and what they did?"
Greens senator Barbara Pocock described Mr Burrowes as being "hung out to dry" and a "patsy" for PwC for not being able to hand over the report.
"We are being treated like mushrooms here, it is inappropriate, you cannot be confused about it, and neither can your international leaders who you are part of the club with," she said.
"That is what you are doing, you are disdaining the parliament."
The inquiry was set up following revelations one of PwC's partners used confidential briefings from Treasury to get clients.
The consulting firm boss said the organisation had taken steps to restore integrity to PwC following revelations of the leaks.
"We are no longer in the advisory business with government .... the making of donations to political parties is something which happens, but we will no longer do it," Mr Burrowes said.
The ATO's Jeremy Hirschhorn also expressed frustration that PwC had not provided the report. (Mick Tsikas/AAP PHOTOS)
Earlier, Australian Tax Office executive Jeremy Hirschhorn raised concerns about PwC's reluctance to hand over the report.
"We share the frustrations of this committee that an organisation which claims to be co-operative is deliberately hiding behind the difference between their local firm and the international firm," Mr Hirschhorn told the committee.
"It's fair to say PwC is very aware of the interest of the Australian community in that document.
"It would be preferable if that was (provided) in a spirit of true co-operation."
Tax Practitioners Board chair Peter de Cure said he'd also not seen the list of six names mentioned in the report, but had a reasonable idea of who they were.
"We have asked for the report formally, and the response we got was that PwC Australia don't have a copy of it, and are not able to give it to us," he said.
However, the board's chair said the Linklaters report was unlikely to form the basis for the organisation's own investigations.
Mr de Cure confirmed the Tax Practitioners Board was carrying out nine investigations into the conduct of PwC, with three of those being "well advanced", which would assist the remaining six.
Mr de Cure said the ball was in PwC's court for cultural change, however, he indicated that such steps would take time to implement.
"The best thing I can say about the big four accounting firms, they're a bit like a cruise ship," he said.
"They're really big machines, they're hard to stop, hard to slow and hard to turn, so the leadership of PwC has a significant challenge to implement a new culture."
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