The office of Federal Health Minister Greg Hunt has been vandalised with anti-mask graffiti.
The vandals stuck masks on Mr Hunt's Victorian office with the words "don't" and "won't", along with a poster that said "I have a condition that prevents me from wearing a mask, it's called intelligence".
From Thursday, everyone in Victoria's lockdown regions of metropolitan Melbourne and Mitchell Shire must wear masks when they are in public.
They risk a $200 fine for not following the new rule, while people in regional Victoria are also being encouraged to wear masks as a precaution.
A spokesperson for the minister told SBS News the matter had been referred to local police and the Australian Federal Police.
"Items were attached to the front door of Federal Health Minister Greg Hunt's Flinders electorate office overnight and were seen when staff arrived this morning," the spokesperson said.
"Minister Hunt reminds everyone that COVID-19 is extremely serious and people must abide by their local state or territory government restrictions, including in regards to masks."
On Thursday, Mr Hunt told reporters he fully supported the mask directive.
"I've seen on my way to and from my office a universal adoption of masks ... It is difficult. But Australians and Melburnians are responding magnificently."
He said Melburnians wearing masks were showing "a sense of commitment, a sense of community".
"We are literally all in this together, because our national success depends on Victoria's success."
The state's chief health officer Brett Sutton has stressed the importance of masks as community transmission remains high.

A tram passenger wearing a mask in Melbourne. Source: AAP
"[Masks] won't always be easy ... but they are important, and there are lessons, increasingly internationally, that the jurisdictions that are doing well have introduced mandatory mask-wearing," he said earlier this week.
"Those that haven't, are the ones that are seeing really catastrophic numbers at the moment."
On Thursday, Premier Daniel Andrews announced Victoria had recorded another 403 new COVID-19 cases and five deaths.
The state has now experienced 18 consecutive days of triple-digit increases.
Residents in metropolitan Melbourne are subject to stay-at-home orders and can only leave home for essential work, study, exercise or care responsibilities. It is also mandatory to wear masks in public.
People in Australia must stay at least 1.5 metres away from others. Check your state’s restrictions on gathering limits.
If you are experiencing cold or flu symptoms, stay home and arrange a test by calling your doctor or contact the Coronavirus Health Information Hotline on 1800 020 080.