Victoria reported 127 new COVID-19 infections overnight, the biggest since the pandemic began. It also reported one death, taking the country's total tally to 105.
The border closure between Victoria and neighbouring New South Wales state will become effective at 11.59 p.m. local time on Tuesday, Andrews said.
Coronavirus cases have been rising in Melbourne, Victoria's capital, over the past several days, forcing authorities to enforce strict social-distancing orders in 30 suburbs and put nine public housing towers into complete lockdown.
