Ralph Stewart. Photo by The NZ Herald.

ACC chief executive Ralph Stewart has become the latest scalp in the fallout from the Bronwyn Pullar fiasco, this morning confirming he is resigning after just eight months in the job.

Mr Stewart's resignation comes just a day after a boardroom purge at the state owned accident insurer in which chairman John Judge was effectively forced out of his job and his deputy John McLiskie and another director Rob Campbell were also told they would not be reappointed.

Mr Stewart said the events of recent days and the departure of Mr Judge and the other directors "has brought me to the point where I have decided to step down as chief executive".

"I am deeply frustrated that the benefits of the scheme and the great work we do has been overshadowed by recent events," he said in a statement.

"This has been an incredibly hard decision to take and one that I have considered very carefully.".

Mr Stewart told his workmates he would keep them informed about developments and the appointment of a new chief executive.

"My focus now is on ensuring a smooth and orderly transition and I will continue to share with you further through our weekly video."

Prime Minister John Key and ACC Minister Judith Collins earlier this week refused to back ACC's most senior executives in their dispute with Ms Pullar but did not want to speak more before two inquiries are completed.

Mr Key said there were "genuine questions" over statements made by ACC leaders about the organisation's police complaint against Ms Pullar.

The corporation has come under new pressure after Ms Pullar released a secret recording of a meeting with ACC to TV3's 60 Minutes which appeared to show she made no threats.

The corporation last week insisted Ms Pullar had threatened to make public thousands of accidentally released client files despite the police clearing her of any offence.

Mrs Collins has also refused to discuss Ms Pullar's allegations but said it was a high priority to rebuild the public's trust in ACC.

Among her allegations, Ms Pullar said Mr Stewart would have known that no threat was made in the meeting because he had heard the secret tape in its entirety soon after the police complaint was made. He did not reveal this to reporters when asked about the tape last week.

She argued that the complaints were "sideshows" to the organisation's mishandling of her file, serious privacy breaches, and increasingly unfair treatment of long-term beneficiaries.

The long-running dispute between Ms Pullar and ACC led to the resignation of ACC Minister Nick Smith from the Cabinet and a legal stand-off between his successor, Mrs Collins, and Labour MPs Trevor Mallard and Andrew Little.

- By Adam Bennett of the New Zealand Herald