Prime Minister Scott Morrison has denied knowing about the alleged rape of staffer Brittany Higgins as far back as 2019.

Mr Morrison has been accused of misleading the Australian public following the publication of text messages that appeared to show his office was told of the incident soon after it took place.

Mr Morrison has asked his department to check on whether his office was indeed alerted to the alleged rape within days, after the text messages, which ran contrary to claims the office did not know.

The Prime Minister’s request came after the disclosure of a text message to Ms Higgins, who says she was raped in Parliament House in March 23, 2019, saying her experience had been raised with an adviser in the Prime Minister’s office on April 3.

“He was mortified to hear about it and how things have been handled,” wrote a friend of Ms Higgins, in a text to her about a conversation he had with a colleague in the Prime Minister’s office that day.

In the texts, the male staffer wrote that he spoke to the Prime Minister’s Office (PMO).

“He’s going to discuss with COS (chief-of-staff) – no one else,” her friend went on to write.

It is not clear who the “he” is in the text messages.

Mr Morrison spoke to the head of the Department of Prime Minister and Cabinet, Phil Gaetjens, on Friday morning to add the text to an examination that is looking into a range of matters, including what his advisers knew and when.

But he insists that Ms Higgins’ decision to go public with her claims this week was the first time he had heard about the alleged rape.

Ms Higgins has previously accused the Mr Morrison of ‘victim-blaming’ over his handling of her allegation.

“I have sought to be as open and honest as I can be about this matter,” Mr Morrison said.

“I have told you everything I know about this matter.”

“I set out in the Parliament this week the timetable of when I am advised my office knew about it,” he said.

“I knew about it on Monday.

“It shattered me. It absolutely shattered me.”

Mr Morrison said he is seeking to address issues raised over the alleged sexual assault “in the best possible way I can”.

“We have to deal with issues of culture, which I’m sure you would agree are not confined to the offices of parliamentarians,” he said.

“This is an issue that every workplace deals with.

“I have no doubt it occurs in the media workplaces, offices in law professions or whatever it might be.”

Opposition Leader Anthony Albanese was less than impressed with Mr Morrison’s explanation, saying it “doesn’t pass the pub test”.

“It’s not credible that the Prime Minister continues to say that his office only found out about it this week,” Mr Albanese said.

“And the dissembling nature of his answers before the Parliament are not good enough.

“I’ll say this about Ms Higgins, she has shown great bravery this week.

“For her to not get the respect of getting straight and clear answers about what the response was at the time, about who was told and what they were told at the time, is disrespectful of Ms Higgins.

“I believe Brittany Higgins. Brittany Higgins deserves better than the way that she has been treated with the lack of government transparency this week.”