PM asked Craig Kelly to remove senior aide who was subject of complaints by interns | Craig Kelly

The prime minister, Scott Morrison, demanded the now former Liberal MP Craig Kelly sack a senior aide who is currently the subject of an apprehended violence order and allegations of inappropriate behaviour by young interns.

Guardian Australia understands that the prime minister had asked on a number of occasions for Kelly to remove Frank Zumbo as his office manager, but the MP, who today moved to the crossbenches, did not take action.

Zumbo is the subject of a Guardian Australia investigation in which it has been revealed that young women – some as young as 16 – had gone to New South Wales police to allege inappropriate behaviour in the workplace, including an instance of unwanted touching.

At least six women have made complaints but no charges have yet been laid. Zumbo, a former associate professor of law at the University of NSW, denies the allegations and said they were “uncorroborated” and “misrepresentations”.

When approached by the Guardian last week, Kelly said he was “unaware” there were multiple women who had gone to police with complaints of inappropriate behaviour in the workplace. He said he was aware of the AVO and the criminal investigation and its nature. He said Zumbo “was entitled to the presumption of innocence”. He confirmed he continued to employ Zumbo.

Today at a press conference Morrison was asked about Kelly continuing to employ Zumbo in a role in his office.

“I have long expressed to Mr Kelly my concerns about that staff member and he has long understood my expectations about that staff member,” Morrison said.

Over the past week the Guardian had asked the prime minister’s office about workplace culture in the member for Hughes’ electorate office and sought comment, which was not forthcoming.

However, it is understood the issue of Zumbo’s employment has been a source of contention within the PM’s office for some time.

Morrison is the MP in the neighbouring seat of Cook, also in the Sutherland shire.

In 2018, the then vice-president of the Liberal party Kent Johns, who had been attempting to win a preselection battle with Kelly, sent an email to his moderate colleagues in the NSW Liberal party.

In an email to moderate powerbrokers Sally Betts, a Waverley councillor, and Trent Zimmerman, the federal MP for North Sydney, Johns made numerous allegations about problems within Kelly’s office.

“What disgusts me more than anything is that we are all [aware] of what is said to be occurring in Craig’s office irrespective of him tearing down the party, climate change denial and attacking marriage recognition.

“The treatment of young woman [sic] in his office over the last six years was made aware to all from the prime minister down. The behaviour you walk past is the behaviour you accept,” Johns wrote at the time.

The email was sent to the entire moderate wing of the Liberal executive.