The inspector of the Independent Commission Against Corruption, David Levine, has described the corruption watchdog’s pursuit of the New South Wales public prosecutor Margaret Cunneen as a “debacle”.

Levine told a parliamentary inquiry on Monday that no one would have envisaged that a car accident between a pizza delivery driver and Cunneen’s son’s girlfriend would have led to hearings “in every court up to the highest court in the land”.

The inquiry is examining the inspector’s scathing report into the ill-fated Icac investigation into Cunneen’s conduct.

In a near 40-minute opening statement to the cross-party committee, Levine launched a blistering attack against Icac Commissioner Megan Latham.

“I welcome the opportunity to get a word in ... the word I wish to get in, is ‘debacle’,” Levine said.

The inspector said he would not engage in a “tit for tat” debate but said the ICAC had tried to exploit and abuse its powers while conducting its investigation into Cunneen.

This was done “on an absolutely unproved basis, to attack the reputation of a senior member of a legal profession in this state,” Levine said.

The inspector also lamented the saga, which ensued following Operation Hale, saying it led to the most “demeaning bloodletting between the two major media groups in this country”.

Levine stood by the conclusions in his report last December, which described the operation as a low point in the watchdog’s history. He said he hoped the committee would acknowledge the “the candour I adopted in the report and the methodology adopted in its preparation”.

He also added that he had no personal animosity towards Commissioner Latham but said her response to his report was “extraordinary”.

The report sparked a bitter public feud between the Icac’s commissioner and inspector.

Latham last month told the inquiry that Levine’s report was “fundamentally flawed” and lacked proper factual foundation.

She also tabled the secret phone recordings that sparked the 2014 investigation which examined whether Cunneen perverted the court of justice by allegedly giving her son’s girlfriend advice to fake chest pains to avoid a breath test after a car accident in May of that year.

Cunneen has consistently denied the allegations and the high court in April 2015 ruled the investigation did not fall within the scope of the Icac’s functions.

The parliamentary inquiry on Monday heard the cross-party committee had received legal advice that it could not publicly release the potentially explosive recordings.

Much of the details of the phone taps have already been leaked to the media, purportedly by members of the committee.

