A report that criticised the ICAC investigation into Crown Prosecutor Margaret Cunneen was "fundamentally flawed", the head of the corruption watchdog has told a NSW parliamentary inquiry.

Independent Commission Against Corruption (ICAC) commissioner Megan Latham is giving evidence before a parliamentary committee inquiry into Inspector David Levine's scathing report, which described the ICAC's ill-fated Cunneen probe as the "low point" in the organisation's history.

In her opening statement, Ms Latham told the inquiry that the report was so flawed it should be withdrawn or disregarded.

"The report is so lacking in a proper factual foundation and infected by a denial of procedural fairness, that it should be withdrawn ... or that the committee place no reliance upon it," Ms Latham said.

It found that it was "unreasonable" for the ICAC to conduct Operation Hale, an investigation into whether Ms Cunneen encouraged her son's girlfriend to fake chest pains to avoid a breath test after a crash.

But Ms Latham hit back, accusing Mr Levine of failing to meet his legal obligation to provide procedural fairness to the commission.

The report prompted calls from some quarters for Ms Latham's resignation.

Today she told the hearing that the ICAC had submitted two volumes of documents, which were given to the Inspector before he wrote his report.

Ms Latham said the documents showed that the Inspector had reached unreasonable conclusions in his report, and that the material should be publicly released.

"The volumes include information that should have been taken into account, they undermine the basis for the adverse findings in the report," she said.

The ICAC probe into Margaret Cunneen has been described as the "lowest point" in the watchdog's history. ( AAP: Nikki Short, file photo )

"They address speculative false claims to which the commission has not been able to lawfully respond and the failure to publish the material will continue to unfairly damage and undermine public confidence in the commission."

The material that the commissioner handed to the inquiry includes Crime Commission phone taps, which were among the material the ICAC assessed when it made the decision to start investigating Ms Cunneen.

The parliamentary inquiry adjourned until next week to decide whether Crime Commission phone taps and other material submitted by the ICAC should be released to the public.

Ms Latham will be recalled to answer questions on February 19 and the other witnesses scheduled today, including Mr Levine, will also give evidence that day.

After the report was released last year, Ms Cunneen's close friend, Jeffrey Phillips SC, said it should have serious consequences for both the ICAC and its commissioner.

"I would have thought the Government and Premier [Mike] Baird now have to consider whether this organisation has now gone so far outside its orbit to be almost considered a rogue organisation," he said.

However others, including former ICAC commissioner Anthony Whealy QC, expressed concern that it revealed a toxic relationship that undermined the report's credibility.

"I have to say that some of the inspector's language is so vehement that it tends to take away from the objectivity of the report," Mr Whealy said.

This is the second time Ms Latham has been called before the parliamentary committee to be grilled about the investigation into Ms Cunneen.

Last year the commissioner clashed with the committee's Liberal chairman Damien Tudehope when she refused to answer questions, saying it was beyond the committee's powers.