The names of more than 50 PwC partners and staff who received or shared confidential Federal Government data in the tax leaks affair remain hidden.

A group of around 20 PwC partners are allegedly preparing to campaign the firm over a "lack of accountability" in tax leaks scandal.

Disgraced consultancy PwC is refusing to reveal the “terms of reference” — the instructions it set — for its secret internal investigation into its decade-long tax leaks affair.

An alleged mastermind of the PwC global tax leaks scam has quietly left a role overseeing a powerful Federal Government tax advisory committee run by the peak body of the Australian legal profession.

The embattled Tax Practioners Board will be forced to reveal whether its former chair — who was in charge for the entire PwC tax leaks investigation —recused himself from the probe, including from board meetings.

The long-time chair of the Tax Practitioners Board — who departed immediately before explosive senate hearings into the PwC tax scandal two weeks ago — spent almost a decade working for the same accountancy as disgraced tax practitioner Peter Collins.