Police are reportedly investigating multiple sex crime allegations made against the former Melbourne lord mayor Robert Doyle.

A spokeswoman for Victoria police confirmed on Thursday that police had “spoken with a number of women in relation to historical sexual assault matters”, in relation to an unnamed person.

“At this time it is only in the preliminary stages and the matter is under assessment,” the spokeswoman said.

The comments followed reports in the Australian newspaper that as many as six women have made allegations about Doyle to police, dating back to his time as a teacher at Geelong College 40 years ago.

Doyle’s lawyer, Nick Ruskin, declined to comment to Guardian Australia.

The former Victorian Liberal party leader resigned as mayor in February 2018, two months after a sexual harassment complaint by his council colleague, Tessa Sullivan, was made public.

Sullivan resigned following the complaint. Another councillor, Cathy Oake, also made an allegation against Doyle.

An independent investigation into the City of Melbourne matters by Ian Freckelton QC, released in March, found that Doyle had sexually harassed both women and made four adverse findings against him. A City of Melbourne staff member has also made allegations.

It has been reported that one of the women who have made a formal complaint to police did so after being frustrated at the outcome of the City of Melbourne inquiry.

The lord mayor, Sally Capp, defended the City of Melbourne’s handling of the matter, saying: “We have as an organisation ... been complying with the relevant obligations and responsibilities we have under the [Local Government Act].”

A second investigation into allegations connected to Doyle’s role as chairman of Melbourne Health, from which he also resigned in February 2018, was inconclusive.

Doyle has repeatedly denied the allegations against him.

He has also challenged the Freckelton report in a case that is due before the Supreme Court of Victoria later this month.