The "significantly under resourced" commission is seeking additional investigators to help with the "current investigative burden".

ACT Integrity Commissioner Michael Adams QC said he initially thought the CIT investigation could have been completed in four to six weeks but this was "absurdly optimistic".

He told budget estimates on Wednesday the commission had originally intended to examine only one contract awarded by CIT to a company owned by Patrick Hollingworth, this being a $4.99 million contract awarded earlier this year.

However, Mr Adams said it emerged there were issues with six contracts awarded by CIT to Mr Hollingworth's entities, Think Garden and Redrouge Nominees.

He said more than a million documents associated with the contracts would need to be examined by the commission.

"[The preliminary] fishing exercise for documents has given us well in excess of a million documents," Mr Adams said.

"A vast majority of those will simply be repetitious attachments passed through 20 or 30 emails."

There have already been six preliminary examinations with witnesses but they will need to be recalled alongside an additional 15 witnesses.

The commission has never held public hearings but Mr Adams told the hearings it was looking "increasingly likely" that public hearings will be held over the CIT contracts.

Mr Adams referenced the CIT investigation after he was asked by Opposition Leader Elizabeth Lee whether the commission had adequate resources.

The commission is contracting an additional lawyer and is attempting to second three police officers from the Australian Federal Police to be investigators.

There are currently two investigators and there is one full-time and part-time solicitor.

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Mr Adams said the commission was also conducting eight other investigations.

"The problem with resources is eventually you get it done but you don't want to get it done in two years," he said.

"From a general policy point of view it is vital that we do these investigations as quickly as we can."

Mr Adams said the commission was "significantly under resourced" but he also acknowledged there had been a significant under spend last financial year.

This underspend came about due to a separation with the ACT government's shared services and the fact the commission lost staff they struggled to replace due to recruitment issues.

Ms Lee said she was not surprised to hear that public hearings about the CIT contracts could take place.

"There is no doubt the current CIT contracts investigation has garnered a significant amount of interest from the Canberra community and it is not surprising it is likely public hearings will take place," she said.

"The commissioner has made it clear the investigation is complex with plenty to look into, and it is concerning that he also stated the integrity commission is not being given the full resources and powers it needs to properly investigate these issues."

The commission announced its investigation into the CIT contracts in June. It was the first time the commission had publicly confirmed an investigation.

More than $8.5 million has been awarded to Mr Hollingworth's companies, Think Garden and Redrouge Nominees, over the past five years to help CIT with its organisation transformation.

The CIT board was not able to guarantee if the $4.99 million contract represented value for money and they claimed they had no oversight of this.

CIT chief executive Leanne Cover, who oversaw the awarding of the contracts, has been stood down on paid leave for the "duration of the inquiries and investigations".

Mr Adams is also continuing to push for telephone intercept powers. He said he needed the powers in order for the commission's current investigations to be conducted properly but did not specifically comment on what investigation this related to.

"[Telephone interceptor powers] is a way of obtaining communications between persons of interest which you cannot otherwise obtain," Mr Adams said.

"We have good reason for thinking that they be in communication and maybe communicating about relevant matters and you're completely excluded from vision of those communications without TI."

Mr Adams said he had written to Chief Minister Andrew Barr asking for a meeting to discuss the matter and was waiting for a response.

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