Victoria has recorded 723 more COVID-19 cases and 13 deaths, Australia's biggest single-day numbers.
Premier Daniel Andrews on Thursday said the latest 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.
The deaths take the state toll to 105 and the national figure to 189.
Mr Andrews also announced a state-wide order for people to wear masks or face coverings from Sunday, across all of Victoria.
Previously regional areas had been excluded from the order but the rising number of cases in regional areas triggered the announcement. Mr Andrews said they wanted to safeguard the country areas before numbers spiralled.
Meanwhile, in NSW, an inmate at Parklea jail has tested positive to COVID-19, prompting a deep clean of the prison area in which he had been isolated.
The man - who had recently been in Victoria - went into NSW custody on Sunday after being arrested for driving offences and refused bail.
Corrective Services NSW says he was isolated from the time of his arrest, underwent mandatory testing in prison and was then housed in isolation.
He had no close contacts in custody and his prison area is being cleaned.
"CSNSW has established Isolation Hubs to safely manage COVID-19 positive inmates separate to other inmates," a spokeswoman said in a statement.
"This is the first and only confirmed case of COVID-19 among correctional staff or inmates at any NSW correctional facility.
"The health and safety of our staff and inmates is our number one priority."
The inmate's case comes amid 18 new NSW coronavirus cases - only two of them in hotel quarantine - recorded on Thursday from more than 27,000 tests.
Meanwhile, tighter restrictions will soon be in place for gyms to ensure social distancing and strict hygiene as the number of NSW COVID-19 cases grows.
Gyms across the state from Saturday will need to register a COVID-safe plan and have a dedicated hygiene marshal on-site to ensure social distancing, equipment cleaning and hand sanitiser availability.
Fitness First gym in Kings Cross - near Sydney's Potts Point coronavirus cluster which now numbers at least seven - confirmed on Tuesday a person who attended an exercise class on July 20 had tested positive.
Other cases in the area are linked to the Thai Rock restaurant in Potts Point - the sister restaurant of the Wetherill Park restaurant where another cluster has formed - and the nearby The Apollo restaurant.
Both restaurants and the Cruising Yacht Club of Australia in Rushcutters Bay were closed on Wednesday for cleaning.
Meanwhile, three Sydney schools have closed on Thursday after recording confirmed or possible coronavirus cases - Fort Street High School in Petersham, Freeman Catholic College in Bonnyrigg Heights and Mary Immaculate Catholic Primary school in Bossley Park.
The latter two have confirmed cases of COVID-19 - the second time Freeman has recorded a case - and have undergone deep cleaning.
The rising number of Sydney cases prompted Queensland Premier Annastacia Palaszczuk to ban entry to all Greater Sydney residents from Saturday.
Other restrictions imposed on NSW residents include a ban on entering Western Australia without an exemption. While travel to South Australia and Tasmania is permitted, people must quarantine upon arrival for 14 days.
Travel to the Northern Territory and the ACT is allowed but people coming from hotspots must quarantine for 14 days, while NSW residents who return from Victoria must self-isolate for 14 days upon return.
Five COVID-19 patients in NSW are in intensive care, with one on a ventilator.
Australian Associated Press