Minister Jill Hennessy ordered the investigation after The Age revealed that a third woman had made an official complaint about Cr Doyle's behaviour.

The fresh allegations relate to his behaviour at a function he attended in his role as chairman of Melbourne Health.

The Health Department has appointed Charles Scerri, QC, to undertake the second investigation.

He will liaise with investigators, led by Dr Ian Freckelton, QC, who are already undertaking an inquiry requested by Melbourne City Council.

Ms Hennessy confirmed she had requested the secretary of the Health Department commission an immediate inquiry, but said it would not be appropriate for her to make any further comment until it was concluded.

On Wednesday, The Age revealed the woman, who does not wished to be named, had been interviewed by two lawyers from Dr Freckelton's investigation team on Tuesday. They told the woman they would also interview her husband.

The woman told the investigators Cr Doyle touched her repeatedly under the table on her upper thigh and made offensive remarks to her at a medical awards ceremony held by Melbourne Health in June 2016.

In response to the woman's allegations this week, Cr Doyle said, via a spokeswoman: "I strongly deny the suggestion that I behaved in any manner that could be construed as inappropriate.

"I attended that event in an official capacity and made a number of speeches and awards throughout the night."

Cr Doyle said he took his responsibilities as the chairman of Melbourne Health "very seriously".

"It is an organisation that I hold in extremely high regard and have had a long and very positive association with," he said.

Asked to respond to the launch of the fresh inquiry, Cr Doyle said he would co-operate fully with the investigation but again strongly denied the suggestion that he had behaved inappropriately.

"As these matters are being addressed within the confines of the investigation, it is not something on which I will comment further."

The lord mayor's alleged behaviour at the gala event made the woman feel so uncomfortable she alerted her partner (now husband), and swapped seats with him, investigators were told.

Two other women have made sexual harassment allegations against the lord mayor.

Former councillor Tessa Sullivan resigned in December after alleging Cr Doyle had harassed and indecently assaulted her. And councillor Cathy Oke has told investigators that Cr Doyle had tried to kiss her, and clutched her thigh under a table in a separate incident.

Cr Doyle has vigorously denied all allegations. He has taken a month's leave from Melbourne City Council and Melbourne Health while the claims are investigated.

The woman and her partner, who is a senior specialist at The Royal Melbourne Hospital, and another family member were invited to the Royal Melbourne Research Gala on June 25, 2016. They were there to watch her partner receive a prestigious research award, she told investigators.

When the trio arrived at the Glasshouse function centre, they were seated at the VIP table, which included Cr Doyle, then-CEO of Melbourne Health Gareth Goodier, and Australia's chief scientist Alan Finkel.

During the event the MC introduced Cr Doyle to the crowd in both his capacity as lord mayor and chairman, the woman says.

The woman was initially "delighted" to be seated next to Cr Doyle, who neither she nor her fiance had met before. "When I sat down I was amazed at how receptive and welcoming he was. He stood up, introduced himself, shook my hand," she said.

Impressed by the venue and event, the woman remarked to the lord mayor she felt it an honour to be there and that he must enjoy attending these galas.

"He said 'no, these events are a yawn'," said the woman. "At that moment we were all offered a drink. And he [Doyle] said: 'The night's only salvation is the red [wine]'."

Taken aback, the woman turned to talk to her partner on her other side. She alleges Cr Doyle then placed his right hand on the top of her left thigh under the table. She moved her leg away, the woman told investigators.

Cr Doyle asked the woman why she was at the event. When she replied the trio were there to see her partner accept an award, Cr Doyle allegedly said "How did you end up with a stiff like that?".

"I was blown away, I thought maybe he was being dry [humoured]," the woman said.

Through the first part of the evening, the woman estimates the lord mayor allegedly touched her on her upper thigh, under the table, "at least eight or nine times".

Feeling intimidated, the woman said she kept moving her leg away from his hand. She did not want anything to detract from her partner's special awards night, she told investigators. The woman said she held her fiance's hand to signal to Cr Doyle that she was not interested in talking to him.

Cr Doyle began to whisper very close to her ear, the woman said. The gala entertainment was a violinist wearing a short, sheer dress, and Cr Doyle allegedly whispered to the woman that she would "look good in that".

"I felt disrespected", said the woman. "He didn't respect me as a person, or the event.

"And I was disappointed, because I had seen him in the media and on the news," she said. "So initially when I saw my name card next to his I was delighted."

Her partner noticed that she looked anxious and uncomfortable, and eventually the woman whispered to him that Cr Doyle was acting inappropriately. They swapped seats.

The woman's husband is furious about the lord mayor's alleged behaviour. He said it put him in a "terrible conflict" as a specialist at the hospital where Cr Doyle is chairman of the board.

"This event was meant to be a family celebration for us ... but has now been forever tarnished by what occurred," he said.

The woman considered reporting the alleged incident but said she felt intimidated by Cr Doyle's status as lord mayor and was concerned her complaint would be given little weight. She also did not want there to be any negative ramifications for her professionally, or for her partner's role at Melbourne Health.

But in December 2017, when the woman and her husband read about Tessa Sullivan's allegations of sexual harassment and indecent assault, they decided to contact Dr Freckelton. They also alerted Melbourne Health to the alleged incident.

Neither the woman nor her husband know Ms Sullivan or Cr Oke. Dr Freckelton is affiliated with a department at the University of Melbourne, as is the woman's husband, but they have never met.

A Melbourne Health spokeswoman said the organisation was "supporting the family of a staff member since becoming aware of an incident at a 2016 function".

It would be inappropriate to provide further comment while Dr Freckelton was conducting an independent investigation on behalf of the Melbourne City Council, the spokeswoman said.

"Melbourne Health is united against sexual harassment, assault or discrimination of any sort," she said.

Ms Sullivan has threatened the Herald Sun with defamation in the wake of a series of articles, including photographs of her in a bikini, that her lawyer claims are "victim blaming" and "intended to discredit" her.

A report from the first investigation is expected to be handed to council chief executive Ben Rimmer by the end of this month.

Know more? mperkins@theage.com.au