Speaking at a press conference Monday morning, NSW Premier Gladys Berejiklian said that "for the next 24 hours the 'hotspots' will extend to all of Melbourne, so no one from the city will be able to cross the border into NSW."
Earlier it was announced that the border between NSW and Victoria, where Melbourne is located, would be temporarily closed from Wednesday morning in order to curb the spread of coronavirus.
In a statement released by NSW government, all travelers returning from Melbourne and the state of Victoria will be required to self-isolate for 14 days and could face "heavy penalties and fines" for non-compliance.
"We have done this based on health advice, and especially given the fact that when our nation had those higher number of cases back in February and March, the vast majority of cases were from overseas travelers or their direct contacts," Berejiklian said.
"What is happening in Victoria is very different, which is why we’ve had to take this necessary step," she added.
The border closure announcement came as Victoria confirmed two additional coronavirus-related deaths on Monday. Australia's death count is currently at 106, according to data collected by Johns Hopkins University.