The admissions came as he closed his evidence to an Independent Commission Against Corruption inquiry into his conduct and as Premier Gladys Berejiklian continued to stand strong against criticism of her defunct relationship with Mr Maguire.

Testifying on Friday, he said he instructed his electoral staff to delete all his records that may have been incriminating after his appearance at a 2018 ICAC inquiry that forced his resignation as member for Wagga Wagga.

"When it became evident that I could no longer retain the position of member for Wagga Wagga ... yes, I told them to wipe everything," Mr Maguire said.

He also admitted a back-up copy of his files on a USB was "dropped" at his farm gate and run over several times, rejecting the suggestion he had destroyed it deliberately.

Mr Maguire also conceded he had told some of his business associates to delete their records too.

Earlier on Friday ICAC apologised to Ms Berejiklian and Mr Maguire, after a transcript of suppressed details of their relationship was accidentally uploaded online.

The transcript of the closed-door hearing, during which Mr Maguire was grilled about sensitive details of their relationship, was available online for more than 30 minutes.

Ms Berejiklian has been forced to defend her integrity after admitting on Monday she had a five-year relationship with Mr Maguire. She insists she had no inkling his dealings may be dodgy.

A transcript of private hearings on Thursday were released on Friday showing Mr Maguire admitted forming a relationship with Ms Berejiklian as early as 2013 and becoming "close" in 2014. Both previously said it began around 2015.

Mr Maguire told the inquiry he did shield the premier from details of his business activities, but had used her as a "sounding board".

"I thought it would cause her difficulties, so I limited the information that I gave her, yes ... obviously, there is a conflict of interest and all that kind of stuff," he said.

Ms Berejiklian on Friday batted away more questions about her integrity.

"Hand on heart, I have done nothing wrong," she said.

Australian Associated Press