SYDNEY, Aug 14 (Reuters) - Leaders from some of Australia's biggest companies, including major banks Macquarie Group ( MCQEF ) and Westpac, will face questioning from lawmakers on Friday as part of a probe into accounting firm KPMG's alleged misuse of client data to win audit contracts.

Macquarie's chairman and chief financial officer, and Westpac's audit committee chair have been summoned before the committee, which will also hear from telecoms provider Optus' CEO and the chair of property firm Dexus ( DEXSF ).

The day-long parliamentary hearing is the second to be called ⁠since whistleblower accusations that KPMG's staff used inside information to ​win lucrative audit contracts came to light in March.

Macquarie, Westpac, Optus and Dexus ( DEXSF ) are all companies caught up in the alleged misconduct by KPMG's senior audit partners. 

While KPMG initially said the allegations were unsubstantiated, the scandal has since led to the resignations of the firm's CEO, audit boss and chairman. 

Additionally, a number of staff implicated in the scandal have either left or been sanctioned after the firm confirmed "unacceptable" misuse of internal documents. 

Deborah O'Neill, a senator from the ruling Labor Party who chairs the committee, said the companies giving evidence were doing a public service by "putting on the record how the failure of this audit sector has actually impacted them in a negative way".

"It's very important that we get on the record the impact of a failure of audit in the corporate sector," she told News24 on Thursday ahead of the hearing.

The KPMG whistleblower, a former senior executive, alleges confidential client files from Lendlease were misused to win audit work with Westpac and Dexus. 

Westpac director Peter Nash has since resigned from the bank's board due to his ties with KPMG. KPMG senior partner Kim Lawry also resigned after Westpac requested her removal as its lead auditor.

Meanwhile, Macquarie has announced it would review the award of its audit contract to KPMG in November 2025. Macquarie director Michelle Hinchliffe was a longtime KPMG employee before joining the board, an association the whistleblower alleged compromised the tender process. 

At the earlier committee hearing in June, then-KPMG chairman Martin Sheppard confirmed Optus data was misused in an unsuccessful bid for work with rival telecoms firm Telstra ( TTRAF ).

Friday's hearing will also feature testimony from current KPMG executives and those who have left the firm in the wake of the scandal.