Gaetjens inquiry into who in Prime Minister's Office knew about Brittany Higgins' allegations of rape suspended

Phil Gaetjens was leading an inquiry into the Prime Minister's Office and its knowledge of an alleged rape inside Parliament House. (ABC News: Ian Cutmore)

An inquiry into who knew what and when within the Prime Minister's office about the alleged rape of former Liberal staffer Brittany Higgins has been suspended for a second time. 

The head of Prime Minister and Cabinet, Phil Gaetjens, confirmed he has put his investigation on hold due to concerns raised by the ACT’s Director of Public Prosecutions that it could “prejudice criminal proceedings now on foot”.

A 26-year-old man was recently charged by police over the alleged assault.

"On the basis of legal advice received on 27 August 2021, I have suspended my inquiry until the conclusion of the criminal trial," Mr Gaetjens said in a statement.

"The action I have taken is strictly in response to the legal advice I have received, and does not relate to any of the content of the inquiry. No inferences in relation to that content can be drawn from the legal advice nor my decision to suspend the inquiry."

Mr Gaetjens said he had informed Prime Minister Scott Morrison of his decision, the second time he has paused his investigations since February.

The inquiry is one of several launched by Mr Morrison after Ms Higgins went public in February, alleging she had been raped by a male colleague inside a minister's office at Parliament House in 2019.

Brittany Higgins alleged she was raped while employed as a ministerial staffer. (Supplied)

While Mr Morrison insisted he first learned of the allegation when the story broke, Ms Higgins said a handful of his staff had been aware long before that. 

Under mounting political pressure, Mr Morrison asked Mr Gaetjens to investigate which staff in the Prime Minister's Office (PMO) knew about the allegation, when they became aware and what they were told.

Next month, the man accused of raping Ms Higgins is due to front the ACT Magistrates Court where he will face "one charge of sexual intercourse without consent", according to ACT Police.

Ms Higgins has given consent through the ACT courts to be named as the complainant.

Given the timing, Monday's announcement by Mr Gaetjens has raised questions about his ability to complete the inquiry in time for the next federal election, which is due by May next year.