Victoria's new cases skyrocketed on Thursday to 723, more than double Wednesday's figure, and there have been 13 more deaths.

Premier Daniel Andrews on Thursday said the mask directive originally issued to residents of metropolitan Melbourne and Mitchell Shire would extend to all regional Victoria from Monday.

The state government will also ban residents of the Colac-Otway, Greater Geelong, Surf Coast, Moorabool, Golden Plains, and the Borough of Queenscliff local government areas from receiving visitors at home from Friday.

"It's inconvenient, it's challenging, but it's essentially stage four for Melbourne and it's something we can do in regional Victoria without causing significant economic cost but get a really significant public health benefit," Mr Andrews told reporters on Thursday.

Prime Minister Scott Morrison said he supported the new measures, stating case numbers in the "Victorian wave" were very concerning.

"We have now been in this lockdown for some weeks and we are not getting the results we would hope for. And as a result the further measures that are taken are certainly necessary," Mr Morrison said.

"They will come at an impact to the economy - we understand that, but equally, not containing these outbreaks will have that effect also.

"And so it's important that we continue to work together to get on top of this and to take whatever actions are necessary."

The prime minister also said healthcare staff working at any of Victoria's virus-riddled nursing homes must wear personal protective equipment or the facilities will be marked down on their accreditation.

Mr Andrews said Thursday's alarming numbers were largely driven by outbreaks in aged care homes.

"There are a number of positive cases in aged care and therefore they are being reflected in these numbers," he said.

"The other issue around targeted testing, where there's been significant outbreaks, the more outbreaks you have, the more testing you do, and you will find cases."

"There's not 700-plus community transmission cases," he said.

Venues such as pubs and cafes in Greater Geelong and the other five local government areas are allowed to remain open amid the latest restrictions.

But data shows family and friends visiting households have driven up infection rates.

"The large part of (transmission) is of course in workplaces," Mr Andrews said.

"But some of the transmission is in households and that makes sense when you think about it.

"People are not necessarily taking the distance in their family time.

"It's a natural thing. You let your guard down."

Regional Victoria has 255 active cases, with 159 in six local areas around Geelong.

Anyone in Victoria who have had positive coronavirus tests are getting a knock on the door by Australian Defence Force personnel or public health officials.

Mr Andrews said several people were not home when door-knocked and some had left to go to work.

"If you are a positive case you need to be at home and you need to be isolating," he said.

Mr Andrews said the latest Victoria fatalities were three men and three women in their 70s, three men and two women in their 80s, and two men aged in their 90s.

Ten of the deaths are understood to be linked to aged care facilities.

The deaths take the state toll to 105 and the national figure to 189.

Australian Associated Press