Victoria's Premier Daniel Andrews announced the decision on his twitter page, saying the rate of community transmission has become too high and the state and its capital, Melbourne "must do more".
Statement on Melbourne moving to Stage 4 restrictions: pic.twitter.com/mFu1Kr1NO0
Advertisement— Dan Andrews (@DanielAndrewsMP) August 2, 2020
Under the restrictions there will be a curfew imposed between 5pm and 8am, with people only allowed to leave their homes to go to work, to seek medical attention or in a caregiving capacity.
A five kilometre travel restriction will be reimposed and people will only be able to exercise and shop within this limit. Each household is only permitted one person to shop for food and essentials each day.
Face covering had already been made compulsory in all outdoor public spaces and this is set to continue. Schools in the state will also close once again.
The state of disaster was used earlier this year during the wildfires which tore through Australia.