By Andrew Brown and Kat Wong in Canberra

Embattled consultancy PwC falsely used legal privileges to withhold documents from tax office investigations, an inquiry has been told.

PwC executives appeared before a parliamentary inquiry on Friday into ethics in the sector, prompted after revelations PwC’s partners had passed on confidential Treasury tax information to boost private sector business for the firm.

Speaking publicly for the first time since the tax advice scandal broke, PwC’s former general counsel Meredith Beattie said the Australian Taxation Office had raised concerns in 2017 about the sharing of confidential material.

But Ms Beattie said PwC had used claims of legal privilege to deny the tax office access to critical documents it had requested as part of investigations.

“Certain parts of the tax group had not been following the protocols, they had not been following the legal engagement letters, and the effect of that mean that the privilege claims that had been made … were not valid,” she told the inquiry.

“I raised the issues with a group within the firm  … and as a result of the letter we had received from the ATO … they were raising very allegations about the firm that was using privilege in  a way that was designed to hide matters from the tax office.”

Former Telstra boss Ziggy Switkowski, who was appointed to lead an independent review into PwC’s Australian operations, said he was not able to speak with previous chief executive Tom Seymour as part of the probe.

Mr Seymour, who will appear before the inquiry on Friday, was the head of PwC’s operations in Australia when the tax advice scandal was playing out.

Mr Switkowski told the inquiry the governance of PwC was poor during the controversy.

“You could see what they were doing and how it was, at least superficially, like every other firm. But in practice it was not really match fit for what they had to confront during that period,” he said.