Australia will isolate 6.6 million people in the state of Victoria from the rest of the nation at 11.59 p.m. on Tuesday, as authorities take drastic action to control a coronavirus outbreak in the city of Melbourne.

The border between Victoria and New South Wales (NSW) -- Australia's two most-populous states -- will be closed for the first time since the pandemic began, Victorian State Premier Daniel Andrews announced Monday.

Military personnel and police will line the border, allowing very few people to cross, according to CNN affiliate 7NEWS.

Victoria has struggled to contain a second wave of coronavirus cases, leading to fears that the infection rate could soon rise across the country. Last week it emerged that some contracted workers in Melbourne were not following protocols at a hotel used to quarantine international arrivals to the state -- including reportedly having sex with people under lockdown.

The surge in cases has forced authorities to reimpose stay-at-home orders on dozens of suburbs and, on Saturday, 3,000 residents of nine densely populated public housing estates were suddenly put under a total lockdown.