Embattled consultancy firm PwC has confirmed it had a second conflict of interest breach in the past five years, but it did not involve the misuse of information.

PwC disclosed the information in answers to written questions on notice by Greens senator Barbara Pocock, who asked:

How many disciplinary actions have been taken in relation to conflicts of interest and/or the misuse of government information in the past 5 years? Past 1 year?

In its reply, PwC disclosed there were two courses of disciplinary actions:

Based on our enquiries, we are aware that the firm has taken action in relation to two matters involving conflicts of interest and/or the misuse of government information in the past five years, including the Tax Practitioners Board matter in which disciplinary action was taken this year. The other matter occurred in 2018.

That action is separate to the current scandal engulfing PwC, involving the use of confidential government information to help clients evade proposed tax changes, which resulted in the sale of its government services division for $1.

In a statement, PwC said the 2018 matter equated to an "internal protocol breach".

"There is no second misuse of information breach," a PwC spokesman said.

"PwC, like other firms, was asked about disciplinary actions and PwC confirmed it had taken discipline against a partner over an internal process oversight where the partner did not obtain approval for an exclusivity undertaking in an engagement."

The 2018 conflict of interest involved a PwC partner entering an exclusivity deal with a client without first seeking approval from PwC's conflict of interest team.

The partner received a financial penalty, and was not fired from PwC.

Public hearings into the inquiry into consulting services are set to resume in Canberra next wek.