Australian Federal Police Commissioner Reece Kershaw has written to Prime Minister Scott Morrison, warning that allegations of criminal conduct should be reported without delay.
His letter comes in the wake of serious allegations made by former Liberal staffer Brittany Higgins, who says she was raped inside Parliament House in March 2019.
The Morrison government has been sharply criticised for its handling of the allegations, including apparent failures to report the accusations to Mr Morrison.
"I cannot state strongly enough the importance of timely referrals of allegations of criminal conduct," Mr Kershaw said.
"Failure to report alleged criminal behaviour in this manner, or choosing to communicate or disseminate allegations via other means, such as through the media or third parties, risks prejudicing any subsequent police investigation.
"Any delay in reporting criminal conduct can result in the loss of key evidence, continuation of the offending and/or reoffending by the alleged perpetrator."
Ms Higgins chose not to take a complaint over the alleged incident further with police at the time over concerns this would impact her career.
Mr Kershaw said members, senators and their offices should refer any such matters referred to them "taking into account the rights and privacy of the victim".
A spokesperson for the Prime Minister says he requested the letter from the AFP commissioner so guidance could be provided to MPs and Senators.
Mr Morrison has also written to the Speaker of the House of Representatives and the Senate President asking for Commissioner Kershaw's advice to be circulated among politicians.
"As we all appreciate, these are serious and traumatic events for anyone to deal with," he said.
"The events of the past fortnight have demonstrated why it is so important that all Members and Senators are informed of their responsibilities in these situations, both to provide compassionate support to those who are affected and to ensure that we uphold the rule of law in dealing with these issues."
A number of federal government ministers were aware of the allegations before they were made public last week.
Ms Higgins's employer at the time of the alleged rape, Defence Minister Linda Reynolds, has since apologised over her handling of the alleged incident.
She says she encouraged Ms Higgins to go to the police when she learned of the alleged crime - as does Ms Higgins’ next boss Michaelia Cash.
Mr Morrison has consistently said his office first knew of the allegation on 12 February but his staff then took almost three days to notify him.
He has expressed disappointment that cabinet ministers did not notify him about the alleged incident earlier.
Ms Higgins has since reinstated her formal police complaint over the alleged incident.
