By Lewis Jackson

SYDNEY Australian senators will use parliamentary hearings this week to demand accounting firm PricewaterhouseCoopers (PwC) name staff and clients who were in on the "big four" firm's misuse of confidential government tax plans.

The staff and clients were referenced in a cache of partially redacted emails released amid a scandal over a former partner at PwC who shared confidential information with colleagues on government plans to crack down on tax avoidance by multinational corporations, then used to drum up business.

Acting CEO Kristin Stubbins, who took the job after her predecessor resigned over the scandal earlier this month, on Monday apologised in an open letter and said nine unnamed partners had been directed to take leave.

Labor Senator Deborah O'Neill, who helped release the emails, said PwC's apology could not be taken seriously and the firm's letter was "another exercise in cover up".

"They provided a curated list of people forced to have a long holiday," O'Neill told Reuters late on Monday, ahead of Economics Legislation Committee hearings on Tuesday and Wednesday.

"They established relationships with 14 of the largest multinational companies in the world. I'm determined to get that on the record."

In response to a request for comment, PwC Australia pointed to its letter on Monday, where it did not name the dozens of staff referenced in hundreds of partially redacted emails and said the vast majority were not knowingly involved in any confidentiality breach.

No confidential information was used to help clients pay less tax, it said in the statement on Monday.

The cache of emails between 2014 and 2017 discuss how confidential drafts of new rules were used to seek work with U.S. technology companies, among others.

The parliamentary committee will hear from the Australian Tax Office and the Tax Practitioners Board and Treasury, which last week referred the matter to police for a possible criminal investigation.

(Reporting by Lewis Jackson in Sydney; Editing by Sonali Paul)