The National Anti-Corruption Commission (NACC) chief Paul Brereton has resigned, two years before his posting was due to end.

Brereton was appointed as NACC's inaugural commissioner in July 2023 for a five-year term, however his tenure had been marred by scrutiny over his external work for defence.

The outgoing commissioner's resignation will come into effect on July 6.

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In a statement, Brereton said that while he "resist[s] any suggestion of impropriety", it was time for him to step aside.

"The ongoing focus on matters relating to me personally rather than the commission's work is drawing attention away from the commission's core purpose of strengthening integrity in the Commonwealth public sector, which has always been my primary focus as commissioner," Brereton said.

"I believe that the commission's success is paramount, and not due to any single person.

"While I will continue to resist any suggestion of impropriety, I have decided that it is time, now that the commission is established and functioning with quality staff and good processes, to step aside and allow a new commissioner to lead it into the next phase of its development into a key and respected component of the integrity architecture of the Commonwealth."

Attorney-General Michelle Rowland thanked Brereton for his service and said a new NACC commissioner would be appointed in due course.

"Commissioner Brereton has made an invaluable contribution to the establishment of the NACC as its inaugural commissioner," Rowland said.

When he was appointed commissioner in 2023, Brereton said it was his ambition to have a commission that was "fearless but fair".

Brereton faced months of scrutiny over alleged conflicts of interest related to his ongoing ties to the Australian Defence Force (ADF) and had been investigated for officer misconduct.

He previously served as assistant inspector-general of the ADF, when he delivered the Afghanistan Inquiry Report.

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