Morrison’s insists he has been open and honest about his knowledge of the incident despite Labor casting doubt on his account.

Higgins is expected to make a formal complaint to police on Wednesday over allegations she was sexually assaulted by a colleague in the ministerial office of Linda Reynolds in 2019.

On Tuesday, Opposition Leader Anthony Albanese told colleagues Morrison lacked credibility in saying he only found out about the incident on Monday last week.

Morrison is sticking to the timeline that his office fielded questions about the incident on February 12 but didn’t tell him for almost three days.

“I have been very open about when I knew about these matters, and indeed when they were brought to the attention of my office,” he told parliament.

Defence Minister Linda Reynolds faltered under pressure in the Senate where she faced another day of questions about her handling of the incident.

She initially revealed a second meeting with the Australian Federal Police after Higgins spoke to them but later appeared unsure.

Reynolds promised to check her records and return to the chamber to confirm.

Higgins is adamant senior members of Morrison’s staff – including one of his most trusted advisers – were aware of the incident in 2019.

The prime minister has asked department secretary Philip Gaetjens, who is also his former chief of staff, to investigate phone records.

But the Gaetjens’ review may never see the light of day, with Morrison waiting to see what the inquiry reveals before deciding on whether it will be released.

Albanese has called for the review to be made public while also criticising the independence of the former senior Liberal staffer.

“After sports rorts I have zero confidence in any process led by Phil Gaetjens,” Albanese told a caucus meeting.

It’s one of four simultaneous inquiries stemming from the rape allegation, which triggered three other women to come forward and allege they were assaulted by the same man.

Morrison said it would be crucial to determine why political staff felt inhibited about raising allegations with police.

“I believe there is an issue to address here, regarding the culture of the workplace of this parliament,” he said.

Government Senate leader Simon Birmingham is working with parties from across the political divide on an investigation into the workplace culture of parliament.

Morrison said he expected the findings would be made public after a quick but thorough inquiry.

Liberal MP Celia Hammond’s review of Liberal Party culture will be absorbed into the cross-party probe.

Birmingham confirmed the accused was not issued a lobbyist pass for unescorted entry to parliament after being sacked from his ministerial adviser job.

But he couldn’t be sure if the man had been signed in because the records were kept manually, making it hard to check.