Victorian Premier Denis Napthine has reportedly been threatened with legal action by the partner of former prime minister Julia Gillard.

An angry voice message left on the premier’s electorate office phone on June 11 came from Tim Mathieson, according to reports, after he was mentioned in Victorian parliament during a debate about the now-suspended MP Geoff Shaw.

The message, broadcast on the Seven Network, includes threats of legal action and refers to Dr Napthine, a veterinarian, as “Denis the vet”.

“Of course you’re busy because you’ve been bullsh**ting all day in Parliament,” the message broadcast on the Seven Network says.

“So, if he mentions the prime minister’s partner one more time, one more time, there will be a legal action against Denis the vet.”

Mr Shaw was suspended for using his taxpayer-funded car for his private hardware business.

During debate about Mr Shaw, Dr Napthine referred to a News Corp article from September 17, 2013 that reported Ms Gillard had written a personal cheque for $4243 to the Department of Finance because Mr Mathieson had used her taxpayer-funded car to sell shampoo and hair-care products in Victoria.

“In those contexts it is very important that we look at the precedent of similar cases in Australia and across the world where there have been allegations and even admissions of misuse of parliamentary resources and what action has been taken in those cases,” Dr Napthine told parliament on June 11.

The voice message reportedly left by Mr Mathieson said there was to be no more mention of him.

“I am not, I am not, anything to do with Geoff Shaw, in any way, shape or form,” the caller said, News Corp reports.

“So, if he mentions me one more time, I am telling you right now. OK? That’s it. Bang!”

News Corp said Mr Mathieson declined to comment on the message and the phone used to make the call had been disconnected.

Victoria’s Attorney-General Robert Clark said if Mr Mathieson did leave the message he must explain himself.

“Debates in the parliament are free ranging and people are fully entitled to put the point of view and the materials before the house that they wish to,” Mr Clark told reporters in Melbourne on Sunday.

“If this phone message was left by Mr Mathieson, he needs to explain himself.”