Weeks after Health Minister Meegan Fitzharris ordered a system-wide, "root and branch" review of the data problems, the audit office has confirmed it is considering starting what would be the fourth audit in seven years to examine data-related problems inside ACT Health and Canberra Hospital.

It follows ACT Health last year contracting PricewaterhouseCoopers to review the directorate's quarterly performance reports.

That review led to the directorate updating figures in at least 12 months' of quarterly performance reports, which cover various measures of the territory's health system, from cancer treatment to mental health services and emergency department waiting times.

Auditor-General Maxine Cooper has already had an external review of the PwC review completed, by former NSW auditor-general Bob Sendt.

But it is unclear what the recommendations of either the PwC report or the Sendt report were, as neither the government, nor the audit office, has publicly released either of the two review reports.

In a recent ACT Legislative Assembly committee hearing, it also emerged that ACT Health Director-General Nicole Feely was kept abreast of the audit office's commissioning of the Sendt review of the PwC report, but Ms Fitzharris was not.

During questions on the data problems from Opposition health spokeswoman Vicki Dunne, Ms Fitzharris said that she had not heard of Mr Sendt or his work on behalf of the Auditor-General, while Ms Feely said she was aware of the Sendt review, but she had not seen a copy of the report.

A spokeswoman for Ms Fitzharris said in a statement that she was aware at the time that the Auditor-General's office had been "looking into" the issues, but not of Mr Sendt's report and that report was a matter for the Auditor-General.

"The Auditor-General is independent of government and her work to review or look into the ACT Health data and reporting issues is a matter for her," she said.

"The minister welcomes any inquiry that the Auditor-General may undertake regarding ACT Health, including specifically ACT Health data."

Ms Fitzharris' spokeswoman also said the government was working to identify all affected reports and that Ms Fitzharris was "absolutely committed to resolving these issues".

"This is a priority for this government, and we will continue to be open with the community and our key health stakeholders about progress in these matters," she said.

The audit office received last year a public tip-off to conduct the audit, but the office would not divulge any details about that tip.

Ms Feely formally wrote to Ms Cooper last September asking for an audit to be completed this year.

That letter was tabled in the Assembly last week and shows that after an error was found in the third quarter performance report for 2015-16, health staff investigated the issue, revealing "probable issues in the extraction code used to generate the data".

That, Ms Feely wrote, led to the discovery that "standards were not used to guide consistent data extraction processes", and "variances" were found in data for 2015-16 and earlier years.

"Given the issues that have transpired to date, I formally request that a review of ACT Health performance and data processes be planned on your audit cycle for next year," the letter reads.

Acting Auditor-General Bernard Sheville said Mr Sendt's report had been obtained to help Ms Cooper decide whether or not to take action "in relation to issues associated with the Health Directorate's management and reporting of performance information, including potential performance audit activity".

But he said she had not yet made that decision and that once a decision was made, the Assembly's Public Accounts Committee would be informed.

Ms Fitzharris has said the "root and branch" review would not report until 2018, but there would be an "update" in September this year.