Authorities are trying to trace a growing coronavirus cluster on the NSW south coast as infection numbers across Melbourne continue to climb.
The Soldiers Club in Batemans Bay has been closed for two weeks after eight people tested positive.
Anyone who dined at the waterfront venue between July 13 and 17 is being urged to get tested and self-isolate.
Sydney residents are being urged to avoid public transport and social gatherings as case numbers increase.
Victoria recorded its second highest daily infection toll over the weekend, despite strict lockdowns measures which have been in place for almost two weeks.
Masks will be mandatory in Melbourne and the Mitchell Shire from Thursday in a bid to curb community transmissions.
Federal cabinet minister Josh Frydenberg lives in Melbourne and supports the new health direction.
“Not in all circumstances can we safely socially distance and in those cases you certainly want everyone wearing a mask,” he told Sky News on Monday.
“I think it is prudent that in Victoria masks are being worn.
“What we need to do is flatten out that curve. It’s going to take a huge effort from the public here.”
Acting Chief Medical Officer Paul Kelly expects it will be several weeks before Victorian case numbers reduce to single figures.
Professor Kelly says he has no regrets about not recommending Melburnians wear masks sooner.
While masks will be mandated in Melbourne and Mitchell, he says it’s up to individuals if they want to wear one in other parts of the country.
“We’ve got a very different situation in Melbourne now where we have community transmission which is continuing to grow,” he told ABC radio.
“This is another step that has been put into place in that context.”
Hundreds of extra Australian Defence Force personnel will hit the ground in Victoria this week to help the state’s fight against coronavirus.
An extra 272 ADF personnel will join 1200 already helping with border controls and contact tracing.
The federal government is also providing one million more masks for Victorian workers in aged care and disability centres, plus five mobile virus testing teams.
Health Minister Greg Hunt apologised to people inconvenienced by the mask-wearing rules.
“We are sorry that it has reached this point for all those who are affected,” he told reporters.
“But this is about saving lives and protecting lives.”
Victoria recorded 363 new coronavirus on Sunday and another three deaths, two men and a woman all in their 90s, bringing the state toll to 38 and the national figure to 122.
NSW confirmed 18 new cases in the 24 hours to 8pm on Saturday, with Mr Hunt acknowledging the state was facing a “Herculean tracing task”.
NSW is imposing harsher border restrictions with Victoria, tightening the permit criteria for southerners wanting to go north.
An inquiry into Victoria’s bungled hotel quarantine program will begin on Monday, after breaches by security guards at two Melbourne hotels led to virus outbreaks.